1.1     Introduction   
   
Welcome to the world of data communications.  You have acquired one 
of the finest intelligent desktop   data/fax modems available today, 
model MT1432BA, from Multi-Tech Systems.  Your MT1432BA modem   
provides data communication at 14,400-9600 bps (V.32bis/V.32), as 
well other prevalent datacomm standards. The MT1432BA also includes 
adaptive protocol enhancing used in typical Unixr batch file   
transfers and support for IBM's AS/400TM and System3xTM environment.    
This Owner's Manual will   help you install, configure, test and use 
your MT1432BA data/fax modem.   
   
1.2     How To Use This Manual   
   
This manual is divided into nine chapters. There are also several 
appendices at the end of this manual, most  of which repeat information  
contained in the chapters, but in a more condensed form. These appendices can   
be used as a quick reference.  The information contained in each 
chapter and appendix is as follows:   
Chapter 1 - Introduction and Description   
This chapter begins with a short introduction, followed by a guide 
(which you are now reading) to the use of this manual. There is a discussion 
about what components you can expect to be in the MT1432BA package.   
We then provide a more detailed description of the modem, as well as 
the modem's technical specifications.    

Chapter 1 includes sections covering power, LED indicators and a brief 
summary of PC board controls.    
(Chapter 8 covers switch settings more thoroughly.)   

Chapter 2 - Installation and Connection   
This chapter covers the information for connecting the MT1432BA to 
your terminal/computer and the phone lines and also which RS232C circuits 
are used.  Chapter 2 explains how to install your MT1432BA   
modem to the point of operation.  You will also find an illustration 
showing the modem's back-panel connectors.   

Chapter 3 - Manual Dial and Automatic Answer   
This chapter covers some modem operations, but delays discussion of 
Command mode operation until   

Chapter 4.  This chapter covers Manual Dial mode, and Answer mode 
operation in detail, as well as the handshaking procedures employed 
between two modems in an auto-answer application.  There is also some   
discussion of various ways of how to terminate a call.   

Chapter 4 - AT Command Mode Operation   
This may be the most important chapter of this manual.  It begins with 
an introduction and discussion of the MT1432BA Command Mode fundamentals.  
A flow chart is provided to illustrate Command Mode and On-  
Line Mode operation and the methods used in each mode.  Next, there 
is a summary of the modem's commands and responses.  We then go into a 
detailed explanation of each MT1432BA command, providing examples where 
applicable.   
   
Chapter 5 - S-Registers   
This chapter covers the MT1432BA's S-Registers, which are used to 
store and/or configure various modem options. All of the S-Registers are 
charted and explained, followed by instructions on accessing the S-  
Registers and reading or changing their values.   
   
Chapter 6 - Callback and Remote Configuration   
This chapter covers how the MT1432BA's Callback and Remote Configuration 
features operate.  This Chapter describes the usage of LOGIN Passwords,
Set-Up Passwords and Remote Escape Characters as network management tools.                                       
				  
			   
Chapter 7 - Testing Your Modem   
This Chapter covers the modem's built-in test features.  These are: 
Power-on Self Test, Local Analog Loopback, Digital Loopback and Remote 
Digital Loopback Tests.  We have included a description of each test and 
how to use each test procedure.   

Chapter 8 - DIP-Switches and Jumpers   
The MT1432BA printed-circuit board options are covered in this chapter.  
Sixteen DIP-Switch settings, several berg jumpers,and the modem's speaker 
volume control are explained in detail, including all default   
settings.   

Chapter 9 - Service, Warranty, Technical Support & BBS   

Chapter 9 provides instructions for getting modems serviced at the 
factory, statements on your five-year warranty and information about our 
user Bulletin Board Service (BBS).   
Appendix A - ASCII/HEX/Decimal Conversion Chart (not in this text version)  
Appendix B - Pulse Dial and Tone-Dial Frequencies   
Appendix C - AT Command Summary   
Appendix D - DIP Switch Summary   
Appendix E - S-Register Summary   
Appendix F - Result Code Summary   
Appendix G - V.25bis Operation   
Appendix H - MT1432BA Cables    
Appendix I - RS232 Interface Specifications   
Appendix J- Multi-Tech Systems' Escape Methods   
   
1.3     What is in Your Modem Package?   
							   
Your MT1432BA is made up of many components. Make sure you 
have them all before trying to operate   
your modem.  Your package should include:   
       MT1432BA data/fax modem (Figure 1-1)   
       RJ11 telephone cord    
       AC Power Transformer   
       This MT1432BA Owner's Manual       
If any of these items are missing, please contact Multi-Tech Systems, or 
your dealer/distributor.   
   
   
   
   
Figure 1-1. The MT1432BA Modem   
   
1.4     Description   
								   
Your MT1432BA modem is designed according to the international 
CCITT V.32bis specification for data signalling rates as high as 14400 
bps full-duplex mode connections on Public Switched Telephone   
Networks (dial-up/2-wire lines). The MT1432BA also supports CCITT V.17 
Group 3/EIA TR-29 Class 2 fax operation. This enables the   
modem to send and receive text, graphics and images to and from any 
Group 3 fax machine. The MT1432BA is downward compatible at speeds as 
low as 300 bps.  This means the MT1432BA communicates with other vendor's 
V.32bis compatible modems, which insures your modem against obsolescence.   
The modem's reliable full duplex performance at high speeds over dial-
up/2-wire lines is made possible through the latest trellis coding, 
echo cancellation, and automatic adaptive equalization techniques, and its   
VLSI technology makes the MT1432BA both small and affordable.   
The MT1432BA is AT command set compatible and incorporates a 
number of capabilities beyond the basics of V.32bis operation. Other 
capabilities include CCITT V.25bis standard for synchronous/asynchronous 
dialing, compatibility with CCITT V.42 error correction and V.42bis data   
compression in which data communication speeds can approach 57,600 
bps (depending on the file content and the receiving modem's capability) 
and the data sent will be 100% error free. V.42 error correction   
incorporates both MNP Classes 3, 4 and LAPM. Data compression can 
be V.42bis for 4 to 1 throughput improvement or the popular MNP Class 
5 for 2 to 1 throughput (depending on file content).   
The MT1432BA offers interactive automatic dialing capability, as well 
as Command mode option configuration. Up to ten command line/telephone 
numbers, of up to 60 digits each, can be stored in the  modem's 
non-volatile memory. The modem uses pulse and/or tone dialing methods, 
and has the ability to recognize dial tones and busy signals for reliable 
call-progress detection; and the MT1432BA has the capability to detect 
AT&T "call card" tones for the purpose of accessing the user's calling 
card before an on-line connection is made. The MT1432BA is FCC-Registered 
for connection to the telephone networks. No Data Access Arrangements 
(DAA's) are required. Callback Security provides MT1432BA users with a 
new means of protecting their networks from unauthorized users.  By use 
of the modem's automatic login routines and phone number/password directory,   
host sites can, after receiving a call, "callback to" a remote site at a 
predetermined number.  This feature can  also be used to reduce phone 
line costs for users through host site call origination.   
Remote Configuration gives users network management capability.  
Users can configure modems at remote sites from local modems, without 
having to visit the sites or rely on users to follow instructions.   
								
	1.5     FCC Regulations for   
Telephone Line                           Interconnection   

1.      This equipment complies with Part 68 of the Federal 
Communications Commission (FCC) rules. On the outside surface of this 
equipment is a label that contains, among other information, the FCC   
registration number and ringer equivalence number (REN). If 
requested, this information must be provided to the telephone company.   

2.  A  suitable jack (Universal Service Order Code connecting 
arrangement) for this equipment is needed (see section 2.3). If applicable, 
the facility interface codes (FIC) and service order codes (SOC) are   
required.   

3.      The ringer equivalence number (REN) is used to determine the 
quantity of devices which may be connected to the telephone line. Excessive 
REN's on the telephone line may result in the devices not ringing   
in response to an incoming call. In most, but not all areas, the sum of 
the REN's should not exceed five (5.0). To be certain of the number of 
devices that may be connected to the line, as determined by the total   
REN's, contact the telephone company to determine the maximum REN 
for the calling area.   

4.      If this equipment causes harm to the telephone network, the 
telephone company will notify you in advance. But if advance notice 
isn't practical, the telephone company will notify the customer as soon as   
possible. Also, you will be advised of your right to file a complaint with 
the FCC if you believe it is necessary.   

5.      The telephone company may make changes in its facilities, 
equipment, operations, or procedures that could affect the operation of 
the equipment. If this happens, the telephone company will provide   
advance notice in order for you to make necessary modifications in 
order to maintain uninterrupted service.   

6.      If trouble is experienced with this equipment (the model of 
which is indicated below) please contact Multi-Tech Systems, Inc. at the 
address shown below for details of how to have repairs made. If the   
trouble is causing harm to the telephone network, the telephone 
company may request you remove the equipment from the network until the 
problem is resolved.   

7.      No repairs are to be made by you. Repairs are to be made only 
by Multi-Tech Systems or its licensees. Unauthorized repairs void 
registration and warranty.   

8.      This equipment cannot be used on public coin service 
provided by the telephone company. Connection to Party Line Service is 
subject to state tariffs. (Contact the state public utility commission,   
public service commission or corporation commission for information.)   

9.      If so required, this equipment is hearing-aid compatible.   
Manufacturer:                   Multi-Tech Systems, Inc.                        
Trade   
Name:                           MultiModemIITM   
Model Number:                   MT1432BA   
FCC Registration #:             AU7USA-65636-
MD-E            Ringer   
Equivalence:                    0.5B                            
				  
		
		Modular Jack (USOC)                             
			  
	RJ11C or RJ11W (single                                  
		line)   
	Service Center in USA:          Multi-Tech Systems Inc. 
					2205 Woodale Drive                      
					Mounds View, MN 55112                                   
					Voice (612) 785-3500                                                   
					FAX (612) 785-9874    
								
	   
1.6     Canadian Limitations Notice        
Notice: The Canadian Department of Communications (DOC) label 
identifies certificated equipment. This certification means that the 
equipment meets certain telecommunications network protective, operational   
and safety requirements. The Department does not guarantee the 
equipment will operate to the user's satisfaction.   
Before installing this equipment, users should ensure that it is 
permissible to be connected to the facilities of the local 
telecommunications company. The equipment must also be installed using 
an acceptable method of connection. In some cases, the company's inside 
wiring associated with a single line individual service may be extended 
by means of a certified connector assembly (telephone extension cord). 
The customer should be aware that compliance with the above conditions may 
not prevent degradation of service in some situations.   
Repairs to certified equipment should be made by an authorized 
Canadian maintenance facility designated by the supplier. Any repairs or 
alterations made by the user to this equipment; or equipment malfunctions,   
may give the telecommunications company cause to request the user to 
disconnect the equipment. Users should ensure for their own protection 
that the electrical ground connections of the power utility, telephone 
lines and internal metallic water pipe system, if present, are connected 
together. This precaution may be particularly important in rural areas.   
Caution: Users should not attempt to make such connections themselves, 
but should contact the appropriate electric inspection authority, or 
electrician, as appropriate. The Load Number (LN) assigned to each terminal 
device denotes the percentage of the total load to be connected to a  
telephone  loop which is used by the device, to prevent overloading. The 
termination on a loop may consist of any combination of devices subject 
only to the requirement that the total of the Load Numbers of all the 
devices does not exceed 100. The Load Number for this product is 5.   
This digital apparatus does not exceed the Class B limits for radio noise 
for digital apparatus set out in Department of Communications.   

1.7     Technical Specifications   
							
Your MT1432BA data/fax modem  meets the specifications listed below:    

Tradename               MultiModemIITM   

Model Numbers           MT1432BA, MT1432BAI, MT1432BA-MAC   

Data Rates (modem)      14,400, 9600, 4800, 2400, 1200, 0-300 bps   

Data Rates (fax)        14,400, 9600, 4800 bps   

Data Format             Serial, binary, asynchronous at 0-300, 1200, 2400, 
			4800, 9600 bps; synchronous at 1200, 2400, 4800, 
			9600 bps   

Compatibility           CCITT V.42bis, V.42, V.32bis, V.32, V.21*, 
			V.22bis, V.22, V.23*,V.25bis, Bell 212A and 103/113, 
			CCITT Group 3 T.4, T.30 and EIA TR-29 Class 2 
			(*V.21/V.23 Int'l models only)   

Error Correction        V.42 (LAP-M or MNP 3 & 4) error correction   

Data Compression        V.42 bis, (4:1 throughput) or MNP 5 (2:1 throughput) 
			data compression   

Speed Conversion        Serial port data rates adjustable to 300, 1200, 
			2400, 4800, 9600, 19,200, 38,400 and 57,600 bps   

Flow Control            Xon/Xoff, Hardware RTS/CTS, ENQ/ACK, Options Unix-to-
			Unix Copy Protocol (UUCP) "Spoofing"   

Mode of Operation       Half or Full duplex over both dial-up lines and 
			2-wire leased lines; automatic or manual dialing, 
			automatic or manual answer   

Intelligent Features    Fully "AT command" compatible, microprocessor 
			controlled remote configuration, autodial, redial, 
			repeat dial, dial linking, pulse or tone dial, dial 
			pauses, call status display, auto-parity and data 
			rate selection, keyboard-controlled modem options, 
			non-volatile memory and on-screen displays for modem 
			option parameters and up to ten telephone numbers/
			command lines of up to 60 digits each, help menus    
			Command Buffer  60 characters   

Modulation              Trellis Coded Modulation (TCM) at 14,400, 12,000, 
			9600 bps, Quadrature Amplitude Modulation (QAM) at 
			9600 (non-trellis), 4800 and 2400 bps, PSK at 1200 
			bps, FSK at 300 bps   

Fax Modulations         V.21CH2 FSK at 300 bps   
			V.27ter DPSK at 4800 and 2400 bps   
			V.29 QAM at 9600 and 7200 bps           
			V.17 TCM at 14400, 12000, 9600, and 7200 bps   
   

Fax Carrier             V.21CH2 (Half Duplex)              
Frequencies             1650Hz Mark, 1850Hz Space for Transmit Originate   
			1650Hz Mark, 1850Hz Space for Transmit Answer   
			V.27ter 1800Hz Originate/Answer   
			V.29 QAM 1700Hz Originate/Answer        
			V.17 TCM 1800Hz Originate/Answer   
   
Carrier Frequencies     1800 Hz  V.32bis/V.32   
			14.4K/12K/9.6K/4.8K   
   
Carrier Frequencies     Transmit Originate:     1200 Hz   
2400 & 1200 bps         Transmit Answer:        2400 Hz   
(V.22bis/V.22 or        Receive Originate:2400 Hz 
Bell 212A Standard)     Receive Answer: 1200 Hz   

Carrier Frequencies,    1270 Hz Mark, 1070 Hz Space for   
300 bps                  Transmit Originate   
(Bell Standard)         2225 Hz Mark, 2025 Hz Space for   
			 Receive Originate   
			2225 Hz Mark, 2025 Hz Space for                         
			 Transmit Answer                   
			1270 Hz Mark, 1070 Hz Space for                         
			 Receive Answer   

Carrier Frequencies     980 Hz Mark, 1180 Hz Space for   
V.21                     Transmit Originate                              
			1650 Hz Mark, 1850 Hz   
			 Space for Transmit Answer         
			1650 Hz Mark,1850 Hz Space for                               Receive 
			 Originate                         
			980 Hz Mark, 1180 Hz Space for                  
			 Receive Answer   
V.23                    390 Hz Mark, 450 Hz Space for                   
			 Transmit Originate                
			1300 Hz Mark, 2100 Hz Space for                 
			 Transmit Answer                   
			1300 Hz Mark, 2100 Hz Space for                 
			 Receive Originate                 
			390 Hz Mark, 450 Hz Space for                   
			 Receive Answer   
Transmit Level  
		     -10dBm (dial-up), 0 dBm (leased-line); dBm level 
		     selectable with DIP-Switch #3 in leased line setting   

Frequency Stability     0.01%   

Receiver Sensitivity    -43 dBm under worst case conditions   

AGC Dynamic              43 dB   
Range      

Interface       EIA RS232C/CCITT V.24   

Connectors      One DB25 RS232C connector; two RJ11 for phone 
		line and telephone set; power   

Diagnostics     Power-on Self Test, Local Analog Loop, Local 
		Digital Loop, Remote Digital Loop.   

Indicators      LEDs for Transmit Data, Receive Data, Carrier 
		Detect, 14,400 bps, 9600 bps, 4800 bps,   
		2400 bps, 1200 bps, Off Hook, Terminal Ready, 
		Error Correction and Fax   

Controls        Toggle switches for Voice/Data with Originate or Answer, 
		Power On/Off; Option Jumpers and   
		DIP Switches for various modem options.   

Speaker         Speaker for call progress monitoring   

Operating       0 to 50 C  (32 to 120 F)   
Temperature   

Power           115 Volts AC, 60Hz, 0.3amp (2-prong outlet-   

Requirements    mounted transformer) 240V/50Hz optional 
(International).   

Dimensions      6.150" x 9.00" x 1.375"   
		15.6 cm x 22.9 cm x 3.5 cm   

Weight  1.6 pounds/0.72 Kg (without transformer)   
	2.6 pounds/1.18Kg (with transformer)   

Limited Warranty        Five Years   
   


1.8     Power   
      
     Power is supplied through an AC power transformer terminated with  a 
     standard  two-prong plug.  The transformer supplies low voltage 
     AC to the modem, and plugs into any conventional 115 volt AC, 60 Hz,   
     two-prong power outlet.  The power transformer supplied with the 
     modem is the only one that should be used.  Use of any other 
     transformer could cause damage to the modem.  A Power On/Off 
     switch is located on the back of the modem.          

1.9     Modem LED Indicators        
The MT1432BA has twelve diagnostic LED indicators.  They are:   
   
1)  Transmit (Send) Data (SD).  This LED blinks when data is being 
transmitted, on for a space, off for a mark.  The state of this LED 
matches the TD circuit on Pin 2 of the RS232C/V.24 interface.   

2)  Receive Data (RD). This LED blinks when data is being received, 
on for a space, off for a mark.  The state of this LED matches that 
of the RD circuit on Pin 3 of the RS232C/V.24 interface.   

3)  Carrier Detect (CD).  This LED is lit when a valid carrier tone has 
been detected.   

4)   14400 bps (14.4).  This LED is lit when the modem is connected at 
14400 bps.  Note: if the modem falls back to 12000 bps while in V.32bis 
mode, both 14.4 and 96 LEDs light.   

5)   9600 bps (96).  This LED is lit when  the modem is set for 9600 bps 
operation.   

6)   4800 bps (48).  This LED is lit when the modem is connected at 
4800 bps.   

7)   2400 bps (24).  This LED is lit when the modem is connected at 
2400 bps.          

8)   1200 bps (12).  This LED is lit when the modem is connected at 
1200 bps.   

9)   Off Hook (OH).  This LED is lit when the phone line is "off hook".  
This occurs when the modem is dialing, on-line, or answering a call.  
This LED also flashes when the modem is pulse dialing in Command   
mode.   

10)  Terminal Ready (TR).  When the TR LED is lit, the modem is 
permitted to answer an incoming call.  When it goes off, a connected 
modem will disconnect.  The state of the TR LED matches that of the DTR   
circuit on Pin 20 of the RS232C/V.24 interface.   

11)  Error Correction (EC).  This LED is lit when the modem is set for 
V.42 error correction, and it will flash on and off when data 
compression is activated.   

12)  FAX (FX).  This LED is lit when in connected in FAX mode.   
   

1.10     Controls on PC Board   
The MT1432BA is designed on a single printed circuit (PC) board.  
This board contains one 16-position DIP-Switch (numbered 1-16), a 
2-position "Flip"-Switch and several berg jumpers. The Switches are   
accessible through a cut-out on the side of the modem and the berg 
jumpers are accessible when the PC board is removed from its chassis.  
There is also a knob which is used to adjust the speaker volume. This   
knob is accessible through the modem's rear panel.     
The sixteen DIP-Switches, "Flip"-Switch and berg jumpers control 
various modem options or set default values for Command Mode operation.  
There is a difference in how several of the switches operate   
depending on whether you are in synchronous or asynchronous mode.  
Refer to the switch label on the bottom of the MT1432BA for an exact list 
of the switch functions in asynchronous and synchronous operation.   

Chapter 8 of this manual provides detailed instructions on configuring 
all of the MT1432BA's PC board options.   
   
   
   
2.1     Introduction   
The installation of the MT1432BA consists of making the physical 
connections necessary to render the modem functional with your computer.  
This includes making the proper serial, phone line, and power   
connections.  It is important to remember throughout this manual that 
all commands must be issued in terminal mode.  This is the natural state 
of a computer/terminal; however, if you connect the MT1432BA to   
a PC, you must run a compatible datacomm program to enter terminal 
mode. (Refer to the proper corresponding datacomm software manual for 
this procedure.)  This chapter covers MT1432BA installation and connection. 
The installation process involves:   

1.      Verify remote modem's current configuration settings with 
     your MT1432BA in terms of data compression, error correction, 
     transmission rate, etc. (per Chapter 4, Section 4.4.12/ATL5 and ATL7   
     Commands).   

2.      Attach MT1432BA to dial-up phone lines (Section 2.3.1) 
     and/or leased lines (2.3.2) and verify DIP-Switch #10 and #5 settings.   
     Refer to Figure 2-1.                        
   
3.      Make sure modem and computer/terminal serial port baud 
     rates are adjusted (Section 2.3.2).   

4.      Set both local and remote modems to either Normal 
     (&E0&W0) mode or to Reliable (&E2&W0) mode (Section 2.3.3).   

5.      Verify leased line transmit level (DIP-Switch #3) setting 
     (Section 2.3.3).   

6.      Attach your MT1432BA to your PC or terminal with an 
     RS232 (or V.24) cable (Section 2.4).   

7.      Connect telephone set to phone jack (if desired) (Section 2.5).   

8.      Attach your MT1432BA to the AC Power transformer and 
     plug the AC connector into a live AC outlet (Section 2.6).   

9.      Verify self-test results (Section 2.6).   

10.     Proceed to Chapter 3 of this manual.   
   

2.2     DIP-Switch Settings   
    Most communications software packages have installation procedures 
of their own, which call for certain modem DIP-Switch settings. If you are 
using a package other than MultiExpress, follow the software's instructions.   
The vast majority of installations are similar, with the MT1432BA 
being used to dial up a remote installation where the call is automatically 
answered.  The factory default DIP-Switch settings are based on   
this assumption. Refer to Chapter 8 if the DIP-Switch settings must be 
changed.   
   


2.3     Phone Line Connection   
							
	
	2.3.1    Dial-Up Lines   
The MT1432BA is designed for communications over Public Switched-
Network Telephone lines.  (It can also be connected to 2-wire leased 
lines.)  Connection to the phone system is made via RJ11 type jacks such   
as  an RJ11C or RJ11W.  It can also be connected to an RJ41 or an 
RJ45S jack, but would not use these jack's dB-level programming features.  
The MT1432BA is designed to transmit at  a permissive level of - 10dB.   
The MT1432BA uses two RJ11 jacks to connect the modem to the telephone 
lines, and if desired, a standard telephone set.  One of the jacks is 
labeled Line Jack  and the other is labled Phone Jack. To connect the 
modem to the phone lines, plug one end of the RJ11 cable that is provided 
with the modem into the Line Jack connector and the other into the phone-
company-provided RJ11C or RJ11W modular phone jack.   
Make sure that DIP-Switch #10 is in the UP position (default) when in 
dial-up mode.  DIP-Switch #10 must  be DOWN when in leased line mode.   
   
2.3.2    Leased Lines   
Although the majority of installations involves dial-up lines, the 
MT1432BA can also  connect to two-wire leased lines (sometimes referred 
to as dedicated, private, or 3002 lines).  No special line conditioning is   
needed, and operation is full-duplex over two wires.   
To connect the modem to leased lines, first determine the type of line 
termination provided by the phone  company.  Most  phone companies provide 
a terminal block with a pair of screws.  Some provide a conventional RJ11 
type of connector.  If the RJ11 connector is used, you can use the same 
cable that is used for dial-up connection.  If the screw terminal type 
connector is used, you may need to order the #CA167 cable from Multi-Tech 
Systems. (Refer to Appendix H).  Next, you need to make two DIP-Switch 
setting changes on the modem's PC board.  The first involves DIP- Switch 
#10. This is used to change the modem from dial-up to leasedline operation.  
Place this switch in  the DOWN position to accomplish this.   
The second DIP-Switch change is to set one of the two modems on the 
leased line circuit as the "originate" modem, and set the other as the 
"answer" modem.  Although there is no dialing in leased line operation, 
the two modems still need to have their frequencies reversed so that they 
can talk to each other.  This is what we mean by the terms "originate" 
and "answer".  To do this you must change the setting of DIP-Switch #5.     
When you changed the DIP-Switch #10 setting, you also changed the 
function of DIP-Switch #5.  Now the UP position selects answer mode 
frequencies while the DOWN position selects originate mode frequencies.     
On one of the two modems, place DIP-Switch #5 in the UP position, 
and on the other modem, place Switch #5 in the DOWN position.  It doesn't  
matter which is which, just so you have one of each.   
When switching from dial-up to leased line mode, make certain that 
modem baud rate and serial port baud rate are adjusted correctly to your 
computer.  Many computer's maximum serial port speed is 19.2K bps,   
and in switching from dial-up to leased line mode, the MT1432BA 
defaults to 57.6K bps (see $SB--Serial Port Adjust Command in section 4.4.11.).   
Once you have installed your modem on leased lines, operation is  
simpler than it was with dial-up lines. With leased lines, there is no 
more dialing.  You're always on-line with the other modem as long as there is   
power connected to both modems.   
When the modems are operating asynchronously, both local and remote 
modems should be set identically in either &E2 Reliable or &E0 Normal mode.   
Some leased lines may require alternate transmit levels. The 
MT1432BA provides a choice of either 0 or - 10 dB. To increase the transmit 
level to 0 dB, place DIP-Switch #3 in the DOWN position (default).  This   
should be done only for leased lines and should not be done for dial-up 
lines.  Modems that are set for 0dB transmit level may not work "back-to
-back" (with no phone line).  Call Tech Support for further instructions.   
   
2.4     Computer or Terminal Connections   
Your computer or terminal is connected to the MT1432BA via  the 
modem's RS232C interface connector (or V.24 equivalent).  This connector 
is a standard interface, with a 25-socket female connection.    
Therefore, your computer or  terminal requires a standard RS232C 
cable with a male connector on the modem end, and a male or female 
connector at the computer or terminal end, depending upon the computer   
or terminal connector.  Plug the RS232C cable into the RS232C 
connector on the modem, and secure it with screws which are included in 
most cable hood assemblies.   
	
	
   Pin        multi-tech      eia     CCITT     signal     circuit   
assignment    designation   circuit  circuit    source     function   


    1            pg           --        101       --       Protective 
							   Ground   
    2            SD           BA        103       DTE      Transmitted     
							   Data   
    3            RD           BB        104       DCE      Received Data   
    4            RTS          CA        105       DTE      Request to Send   
    5            CTS          CB        106       DCE      Clear to Send   
    6            DSR          CC        107       DCE      Data Set Ready   
    7            SG           AB        102        --      Signal Ground   
    8            CD           CF        109       DCE      Carrier Detect   
    9**          +v           +v         --       DCE      Test Voltage   
    12           HS           --         --       DCE      High Speed   
    15***        TC           DB        114       DCE      Transmit Clock   
    17***        RC           DD        115       DCE      Receive Clock   
    20           TR****       CD        108/2     DTE      Terminal Ready   
    22           RI           CE        125       DCE      Ring Indicator   
    24           XTC          DA        113       DTE      External        
							   Transmit Clock   
    25           OOS          CN        142       DTE      Terminal Busy   
   
	**Pin 9 need not be present in your RS232C cable   
	***Pins 15 and 17 are necessary only for synchronous 
	   operation   
	****Also known as DTR (Data Terminal Ready)   
   
Although the RS232C/V.24 interface connector is designed for 25 
signal paths, only 14 or 15 of these signals are used  by the MT1432BA.  
If your computer or terminal did not come with an RS232C/V.24   
cable, you can get one from any supplier of computer equipment.  A 
standard "straight-through"  RS232C/V.24 cable will usually work.   
Note: any cables connected to the computer should be shielded to 
reduce interference.   
   
2.5     Connecting a Telephone Set   
If you wish to have a telephone set connected to the same telephone line 
for voice communications, you may plug the telephone set into the modem's 
connector labeled PHONE Jack.  This connector is provided as a convenience.  
It is possible to originate a data call with the MT1432BA using a telephone 
set and the Voice/Data switch.  It is much easier to originate data calls 
using the Command Mode dialing features, and that method is recommended in 
nearly all applications.   
   
2.6     Powering Up   
Power is supplied to the MT1432BA through the AC power transformer included 
with the modem.  This transformer has a 2-prong AC connector, and an attached 
cord with a 2-pin connector at the end.  The transformer bears the Multi-Tech 
logo. Connect the modem's AC power transformer to a live AC outlet, and 
connect  the end of the power cord to the POWER connector on the back of the 
modem. As soon as you connect power to the modem, it performs a diagnostic 
self-test, indicated by the five speed indicators flashing in sequence for 
approximately four seconds, then the 14.4  indicator should light.  If this   
does not  happen, check that the transformer is solidly connected and 
that the AC outlet  is live.  Refer to Chapter 7 for more information on 
modem testing.  The TR indicator should also light at the same time for most 
installations.  The SD, RD, CD and OH indicators should also remain off at 
this time.   
   
3.1    Introduction    
We'll assume that yours is the very common application, where you are 
using a MT1432BA to dial up a remote computer. The MT1432BA modem has 
been factory preset for originating a call to another compatible 
14,400 bps modem (also set up for V.42 error correction, V.42bis data 
compression and CTS/RTS operation).  If the answering modem is not set 
up similarly, the MT1432BA automatically adjusts to the appropriate 
protocol (Bell/CCITT Standards--not proprietary).    
    
3.2    Dialing/On-Line/Answering   
There are several basic steps for "originating" and "answering" in data 
communication mode:   
	1.      Load communication software   
	2.      Dial   
	3.      Establish On-Line connection   
	4.      Terminate Call     

A simple way to dial is from the keyboard of your computer or 
terminal.  You enter a command on the keyboard to tell the MT1432BA to dial.   
If you use one of the more sophisticated communications software 
packages, the software tells you to enter phone numbers and other
information.  If this is the case, the software, and not you, gives the 
dialing commands to the modem.  All of the  commands, option registers and 
intelligent features of the MT1432BA will be taken care of by the software.   
If you are giving commands directly to your modem (and not through 
your software), each command must begin with AT (ATtention Characters). 
AT characters may be entered in upper or lower case.   
Entering AT automatically sets the modem's speed to match the speed 
of the computer or terminal, and also sets the modem's parity.     
The AT characters alert the modem that a command follows.  The AT 
Command can also be used to clear the command buffer, by simply typing 
AT and hitting RETURN.  The letter D in a command causes the modem to dial 
the numbers immediately following it (e.g., ATD6127853500). You have a 
choice of either pulse (ATDP) or tone (ATDT) dialing methods.   
The MT1432BA responds with "CONNECT" on your video display after the number 
is dialed and a connection signal is detected (since the MT1432BA defaults to 
V.32bis/V.42/V.42bis, the actual response is "CONNECT14400 LAPM COMPRESSED"), 
if the MT1432BA "connects" with a similar modem (see section 4.3 Result 
Code Summary).  The modem is now in "On-Line" mode, and is ready to 
communicate   with a host  site.     
If no connection signal is detected within 45 seconds (this time period 
can be adjusted by S-Register S7), the MT1432BA goes On Hook/hangs up and 
returns to Command mode.  At this point, your video displays "NO CARRIER".   
Enter ATH to Hang Up On-Line (bring modem on-hook), and terminate 
the modem's On-Line mode. At this  point, your video displays "OK".    
In addition to the  call originating capabilities, the MT1432BA  can 
also automatically answer incoming calls.  You need not be present.  
You can, however, control the situation by configuring the modem to either   
answer or not to answer, or to answer after a specified number of rings.  
This is done by setting the value of S-Register S0 (modem defaults to 
automatically answer an incoming call after one ring). Refer to Chapter 5   
for S-Register details.   
   
   
3.3     Manual Call Origination   


You can use the MT1432BA to both originate and answer calls.  To 
originate calls in the Asynchronous mode, you will most   
likely use the MT1432BA's Command mode, and give the modem 
automatic dialing commands.  (We will delay our discussion of the 
Command Mode until Chapter 4.)  When using your modem in the Synchronous   
mode, the Command mode is disabled, so you must automatically dial 
your calls with a telephone set.  To use manual dialing, you must first  
connect an ordinary telephone set (either touch tone or rotary dial) to the   
modem's PHONE Jack connector.  Next, you must set the speed 
selection, which is controlled by DIP-Switches #13 and #14, to the speed 
at which you wish to communicate.  These DIP-Switches are located on   
the side of the modem (refer to Chapter 8 for DIP-Switch settings).    
Once your telephone set is connected, you can use it to dial the modem 
you wish to call.  Simply dial the number, and then listen to the dialed 
modem's answer tone.  When you hear it, press the Voice/Data switch   
on the front of the modem down (to the Originate position).  You don't 
have to hold it down.  Just  press it once and let it go.  Once you press 
the switch, the tone you hear should change to another pitch, or change   
into a rough-sounding scrambled noise.  You then replace the telephone 
handset in its cradle, and your data communications can begin.  Note that 
the MT1432BA may call manuallY via the keyboard command ATD, or by pressing 
the Voice/Data switch on the modem's front  panel downward.  To force the 
MT1432BA to automatically answer calls, either type ATA, or press the 
Voice/Data switch on the modem's front panel upward.   
   
3.4     Automatic Answering   
								
The MT1432BA can be used as an automatic answering modem.  No 
special modifications or settings are required other than   
making sure that the Auto-Answer select switch is set to auto-answer 
enabled (DIP-Switch #5 UP). The MT1432BA, when in its idle state, is
set for originate mode frequencies.  An incoming ring signal
automatically switches the modem into answer mode.   
You can program the modem to answer a call after a certain number of 
rings using S-Register S0 (see Chapter 5). Refer to Section 3.6 for 
the handshaking procedures used by the MT1432BA when in automatic   
answer mode.  In many originate only applications, you may wish 
to disable the automatic answer capability of the modem.    
If a telephone set  is connected to the modem, you may wish to receive 
incoming calls in a voice mode for normal voice conversation.  If 
auto-answer is  not disabled, all incoming calls are answered by the modem,   
preventing voice communications. To disable automatic answer, place 
DIP-Switch #5 to the DOWN (Disable Auto Answer) position (refer to Chapter 8).   
Another way to disable automatic answer is to use S-Register S0 to 
configure the modem to answer on the nth ring, where n equals zero (0).  
Another alternative is to have the modem answer after five or six rings,   
which gives you time to answer it manually if you wish.  (See Chapter 5 
for S-Register information.)   
   
3.5     Manual Answering   
								
We have shown that the MT1432BA can automatically answer incoming 
calls.  The MT1432BA can also answer manually, under your control.  The 
most typical application involves you and another person, who, after 
carrying on a voice conversation, want to convert to data communications 
between your modems without having to hang up and dial again. The problem 
here is that both modems are in originate mode. For two modems to 
communicate, one of them must be in originate mode and the other must be in 
answer mode.  The solution here is to force either one of the two modems 
to answer mode, and the other to originate mode.  The MT1432BA can be 
forced into either answer mode or originate mode, using the Voice/Data 
switch on  the front of the modem. In our example, let's say that you and 
your friend Bill have just had a voice conversation.  Both of you have   
your telephones connected to your MT1432BAs, and your modems are 
connected to computers or terminals.  Set the speed switches to 
the proper speed on both modems.  To switch to the data mode from   
the voice mode, you would switch the Voice/Data switch Down (to the 
Originate position), and Bill would switch his up to Answer.  This 
switches your modem to the originate on-line mode, and Bill's to the answer   
on-line mode.  You would both then hang up your telephone handsets, 
and continue the conversation via your keyboards.   
   
3.6     Handshaking Details   
								
								
The following briefly explains what happens between two modems in a 
normal call. We are assuming that there are MT1432BAs at both the 
originating and at the answering end of the telephone line. (If other 
brands of modems are used with our modems, they will still communicate, 
but each manufacturer tends to use slightly different delay   
timings and sequences, and many of the brands vary in their LED 
designations.)   When a call is dialed from the originating modem, 
the called modem responds to the ringing by switching   
into the answer mode and by turning on its RI (Ring Indicator, 
RS232C/V.24 Pin 22) signal as the rings are detected.   
Note that in order for the called modem to be able to answer the call, it 
must have a high DTR (Data Terminal Ready) signal. This signal 
comes from the computer or terminal to which it is attached, on   
RS232C Pin 20.  (Note that the  MT1432BA-MAC does not use DTR.)   
When the called modem answers the call, its OH (Off Hook) circuit 
comes on and the ringing  stops. Two seconds after the call is answered, 
the called modem  begins transmitting its answerback tone.   
The originating modem, which has been off hook and waiting for the 
answerback tone,  turns on its transmitter when it  hears the tone. 
Then after a one second delay, CD (Carrier Detect) will come on.   
The called modem then responds to the originating modem by turning 
on its CD (Carrier Detect) signal, and the handshaking is completed.   
Note: If you are using the Reliable or Auto-Reliable mode, some 
additional handshaking takes place. This is explained in Chapter 4, 
"Auto-Reliable Mode" ( section 4.4.8.).   
   
3.7     Call Termination   
							
There are a number of methods by  which you can terminate a call, 
or simply stated, hang up. They are:   

1.      Command Mode Control. To terminate a call by Command    
	Mode, enter +++ATH then RETURN; or, send a BREAK signal 
	followed by ATH and a RETURN.   

2.      DTR Control. If DTR (Data Terminal Ready) is turned off for 
	50 milliseconds or more, a disconnect occurs. This is 
	probably the most common method used by computer systems 
	at the automatic answer end of the line to cause the answering 
	modem to disconnect after logging off procedures.   

3.      Loss of Carrier. After a data connection is established, the    
	modem  disconnects if a loss of carrier occurs for 700 
	milliseconds (0.7 seconds) or more.  Note that one cause of 
	carrier loss would be if one of the modems were to 
	disconnect normally.   

4.      Abort Timer. Answer Mode: When OH (Off Hook) comes on, 
	the called modem  starts a forty-five-second timer and 
	waits for a carrier signal from the originating modem. 
	If carrier is not detected within this period, the modem  
	disconnects (hang up) and is ready for another call. 
	Originate Mode: The abort timer functions the same as 
	in answer mode, except that the timer begins after the 
	modem has completed dialing, instead of when it first 
	goes off hook. It is possible to change this forty-five 
	second wait period to any other value (from 0 seconds up 
	to 255 seconds), or to disable the timer completely by 
	reconfiguring S-Register S7 (see Chapter 5.)   

5.      Inactivity Timer. Causes the modem to disconnect if no data is 
	being transmitted or received for a specified time. The timer 
	is restored any time a character is passed through the serial 
	port in either a send or receive state. This timer runs in 
	both normal or reliable connections and is controlled by 
	S-Register S30. The Inactivity Timer can be disabled by 
	setting S30 to 0, which is the factory default setting.   
   
   
4.1     Introduction   

AT commands are the means by which you, and your communications 
software, are able to communicate with and configure your modem.  They 
enable you to establish, read, and modify parameters in addition to   
dialing.  The following provides both a summary and a detailed 
explanation of the AT commands recognized by the MT1432BA.   
   
4.1.1    AT Command Editing   

The BACKSPACE  key on your keyboard can be used to edit 
characters in the AT command line. An AT   
command is not executed until the RETURN key is pressed. The 
BACKSPACE key erases the previous character for reentering.   
The BACKSPACE key does not erase the AT characters once they are 
entered. If your keyboard has no BACKSPACE key, CTRL-H does the 
same thing. The character recognized by the modem as   
BACKSPACE may be changed to any other ASCII character with S-
Register S5. If you wish to cancel an entire command that has 
been entered but not yet executed, enter CTRL-X. This   
also clears the command buffer. The effect is the same as backspacing 
to cancel the entire command, only quicker. Characters entered in 
a command are stored in the modem's Command Buffer (memory) until 
executed by hitting RETURN. The Command Buffer's capacity is 
sixty characters. The Attention Characters AT do not   
count  in the sixty allowed Command characters. Spaces, which may be 
used for increased display readability, may be used when entering a 
command, but are not stored in the Command Buffer and are not   
counted in the sixty allowed characters. Hyphens, parentheses, etc. are 
not allowed.  If the sixty character limit is exceeded or if invalid 
characters are entered, the Command Buffer   
automatically erases, and an ERROR message appears. You would then 
re-enter your command within the sixty-character maximum, using 
only the allowed characters.   

4.1.2   Functional Modes   
The MT1432BA can be in one of two functional states (see Figure 4-1).  
These are "Command mode" and "On-Line mode". (There is also an in-between 
state, "Wait-for-Carrier", where the modem is out of Command mode but 
not yet really On-Line. When the modem is initially powered up, it is 
in Command mode and is ready to accept commands from   
your keyboard or software.  The MT1432BA enters On-line mode after 
dialing, making a connection with another modem, and then detecting 
a valid carrier signal.  If no carrier is detected within a certain time   
frame, the modem abandons the call and re-enters Command mode.   
Once on line, the modem exits On-line mode if one of two conditions is 
met.  If the carrier is lost or intentionally dropped, the modem hangs 
up and re-enters Command mode.  Also, if the MT1432BA   
recognizes the Escape sequence for which it is configured (i.e., either 
the Escape characters in the serial   
data stream, the Remote Escape characters in the modulated data 
stream, or the Break signal), the   
MT1432BA will exit On-line mode, retain the datacomm link, and enter 
Command mode.  You can force the MT1432BA into On-line mode without 
dialing by sending the ATD or ATA command to the modem.   
   
   
   
4.2     Summary of AT Commands   

A wide variety of autodial operations and modem options can be 
controlled when the MT1432BA  modem is in Command Mode. A brief 
summary of these commands follows below (remember, nearly all commands   
begin with AT.)  These commands are organized into several functional 
groups. An alphabetical summary of commands is provided in Appendix C.    

HOW TO               COMMANDS   
   
DIAL                 D       Dial   
(Section 4.4.1)      A: or : Continuous Redial   
		     $D      DTR Dialing   
		     $VD     Voice/Data Dialing                 
		     $MI     MI/MIC Dialing   
		     N       Dial a Stored Number   
   
MODIFY DIALING       P/T     Pulse/Tone Dialing   
PROCEDURES           &P      Set Pulse Dial Ratios   
(Section 4.4.2) ,       Automatic Pauses in dialing   
		     Y       Long Space Disconnect   
		     W       Wait for New Dial Tone   
		     ;       Return to Command Mode After Dial Command   
		     R       Reverse Mode of Operation   
		     !       Flash On Hook   
		     $       "Call Card" Tones Detect   
		     @       Quiet Answer   
   
MEMORIZE PHONE   
NUMBERS              D...N       Store Phone Numbers   
(Section 4.4.3)      NN          Number Linking   
		     L       List Numbers Stored in Memory   
	   
	       
STORE MODEM          &F      Load Factory Defaults    
CONFIGURATIONS       &W      Store Configuration & S-Register    
AND DEFAULTS                    Parameters   
(Section 4.4.4)       Z       Reset Modem   
		      V       Result Code Terse/Verbose   
		      $SP     UNIX/"Spoofing"   
		      &M      Sync/Async Mode Select     
		      &X      Synchronous Transmit Clock Select   
   
CONFIGURE             Q       Result Codes Enable/Disable Response   
COMMAND               &Q      Result Code Selection   
RESPONSES             E       Echo Command Characters   
(Section 4.4.5)       V       Result Code Terse/Verbose   
		      X       Result Code...Basic/Extended/Call                         
			      Progress   
	   
   
CONDITION             &G      Guard Tones   
PHONE LINE            M       Monitor Phone Line   
(Section 4.4.6)       &T      Remote Digital Loop Signal   
		      #T      Enable/Disable Trellis Coded Modulation   
		      B       Bell/V.21 Tones   
		      #F      Fallback When On-Line   
		      #A      Auto-Speed Detect                  
CONTROL RS232C        &C      Carrier Detect Control   
INTERFACE             &D      Data Terminal Ready Control   
(Section 4.4.7)       &R      Clear To Send Control   
		      &S      Data Set Ready Control   
		      &RF     CTS/RTS Control   
		      &SF     DSR/CD Control   
   
CONFIGURE             &E0     Normal Mode   
ERROR                 &E1     Auto-Reliable Mode   
CORRECTION            &E2     Reliable Mode   
(Section 4.4.8)       #L0     Negotiate V.42 Mode During Handshake       
		      #L1     MNP On/LAPM Off   
		      #L2     LAPM On/MNP Off   
		      #L3     Direct LAPM/Phase Out Handshake   
		      $A      Auto-Reliable Buffering   
		      $F      Enable/Disable Auto-Reliable Fallback             
Character         
		      $R      Retransmit Count   
		      $E      Error Correction at 300 bps   
   
CONFIGURE             &E3     Flow Control Disabled   
FLOW CONTROL          &E4     Hardware Flow Control    
(Section 4.4.9)       &E5     Xon/Xoff Modem-Initiated   
		      &E6     Xon/Xoff Modem Responds/No Pass-              
			      Through   
		      &E7     Xon/Xoff Modem Responds/Pass-                     
			      Through Allowed   
		      #X      Send Single/Multiple Xoff Characters   
		      &E8     Enq/Ack Off   
		      &E9     Enq/Ack On   
		      &E10    Normal Mode Modem Flow Control Off   
		      &E11    Normal Mode Modem Flow Control On   
		      &E12    Computer-Initiated/Off   
		      &E13    Computer-Initiated/On   
FLOW CONTROL          &BS     Maximum Block Size   
CONFIGURE...          $EB     10/11 bit Asynchronous Format   
(Section 4.4.9)       #P      Parity Selection   
   
CONFIGURE DATA        &E14    Data Compression Disabled   
COMPRESSION           &E15    Data Compression Enabled   
(Section 4.4.10)   
   
CONFIGURE SPEED         $BA0    Speed Conversion On   
CONVERSION              $BA1    Speed Conversion Off      
(Section 4.4.11)        $MB     Set modem speed (e.g.,$MB14400)   
			$SB     Set serial port speed (e.g.,$SB57600)   
   
EXECUTE                 $H      Help   
IMMEDIATE               I       Product Code Inquiry   
ACTION                  L5      List Current Operating Parameters   
COMMANDS                L6      List S-Register Values   
(Section 4.4.12)        
			L7      List additional Configuration Parameters   
			L8        List On-Line Diagnostics   
			H          Off Hook       
			+++AT<CR>               EscapeSequence:Entering    
						Command Mode while On-Line              
			%E      EscapeSequence    
				  Options. . .Entering Command Mode             
				  while On-Line                     
			A       Force Answer Mode                       
			O       Exit Command Mode/Go Back    
				On-Line   
   
READ AND                Sr?      Read Current S-Register Value   
ASSIGN                  Sr=      Assign S-Register Value   
S-REGISTER   
VALUES   
(Section 5.1)   
   
REMOTE                  #CBN    Passwords for Callback Phone Numbers   
CONFIGURATION           #DB     Callback Security Enable/Disable   
& CALLBACK              #I      Change LOGIN Password   
SECURITY                #RCBNxx Erase Password    
(Section 6.1)                   Linked with Memory Location xx   
			#S      Change SETUP Password   
TEST MODEM              U       Self-Test Modem (Chapter 7)        
(Chapter 7)             &T      Enable/Disable Digital Loopback Signal   
   

4.3    Result Codes   
The MT1432BA Command mode provides you with several responses, 
or "Result Codes", that can aid you in Command mode operation.  
These Result Codes are displayed on your video monitor.   
You can choose result codes that closely match those of the standard 
AT command set, or choose enhanced function result codes that 
have been used in Multi-Tech modems ("Multi-Tech" responses).  The &Q   
command selects which result codes will be used.     
You can choose to have these Result Codes displayed  in either 
"verbose" (full words) or "terse" (digits) format.  This is controlled 
by the ATV0 (terse) or ATV1 (verbose) commands. The MT1432BA defaults 
to verbose format.   AT&Q0  selects Multi-Tech responses with 
Reliable/Compression modifiers.  The terse response code for CONNECT 2400 
is 9.  AT&Q1 selects Standard AT command set responses.  The terse 
result code for CONNECT 2400 is 10.   

The following tables define the result codes generated by the &Q 
command (refer to Appendix F for Result Code Summary).   
	
       &Q0 "Multi-Tech" Result Codes   
	
	TERSE           VERBOSE   
	
	0               OK   
	1               CONNECT   
	2               RING   
	3               NO CARRIER   
	4               ERROR   
	5       *       CONNECT 1200   
	6               NO DIALTONE   
	7               BUSY   
	8               NO ANSWER   
	9       *       CONNECT 2400   
		   
	11      *       CONNECT 4800   
	12      *       CONNECT 9600   
	13      *       CONNECT 14400   
	   
   
   
   
* When error correction is used, the word RELIABLE (verbose) or the 
letter R (terse) is added to these responses. When data compression 
is activated, the word COMPRESSED (verbose) or the letter C (terse)   
will be added to these responses.   
 
    &Q1 "Standard AT" Result Codes   
	
	TERSE   VERBOSE                
	0       OK   
	1       CONNECT   
	2       RING   
	3       NO CARRIER   
	4       ERROR   
	5       CONNECT 1200   
	6       NO DIAL TONE   
	7       BUSY   
	8       NO ANSWER          
	10      CONNECT 2400   
	11      CONNECT 4800   
	12      CONNECT 9600   
	13      CONNECT 14400   
	   
   
Error Correction/Data Compression modifiers are not displayed with 
"Standard AT" Result Codes.   
   

4.4    Dialing Commands   

4.4.1    Dialing Action Commands   


Dial          The letter D in a command causes the    
Command       MT1432BA to dial the telephone number 
	      immediately following it. For example, if you    
D             enter ATD5551212 and hit RETURN, the MT1432BA dials 
	      the number 555-1212.   
	      The D command is also used in conjunction with a telephone 
	      set for manual dialing. You dial the number on your 
	      telephone set, and after hearing the answer tone on 
	      your handset, you type ATD on your keyboard and hit  
	      RETURN. Then hang up the headset.  Unless you have a 
	      specific need to dial in this manner, we recommend you 
	      use the first method, where the telephone number is 
	      entered on your keyboard.   The MT1432BA gives you 
	      several choices of dialing methods. You can use tone 
	      or pulse dialing, by inserting a letter T or a P in 
	      the command string. (See Section 4.4.2 on Dial Modifiers).   
	      You can also configure the modem to either wait for and 
	      detect dial tones and busy signals (which we call 
	      "Wait-for-Dial-Tone" dialing or "Smart" dialing), or 
	      work with timed pauses without dial tone and busy signal 
	      detection (which we call "Blind" dialing; see Section 4.4.5, 
	      "X" Command.)   
	
	Note: There is another method of dialing, called "DTR 
	      Dialing", where by manipulating the DTR signal on 
	      pin 20 of the RS232C/V.24 interface, a number 
	      stored in the modem's memory is automatically   
	      dialed. See Section on DTR Dialing ($D command) for 
	      details.   



Continuous Redial       If you select the Wait-For-Dial-Tone method    
(not used in            of dialing (see X3 or X4 command), you can   
MT1432BAI)              command the MT1432BA to continuously redial (up 
			to 10 redials for DOC units) a busy    
A: or :                 number until your call is answered. This is done 
			with the A: command.   
		This command would be used only if you had already reached 
		a busy number after executing a normal dial command. 
		You simply enter A: (you need not enter AT, nor do you 
		need to hit RETURN), and the modem will redial the number 
		for you. If you again reach a busy signal, it redials 
		again and again until it no longer detects a busy signal. 
		You can stop the MT1432BA from redialing by pressing any 
		key.   
		Another method used to cause the modem to redial a phone 
		number continuously is to enter a colon :  at the end of 
		the phone number. The result  is the same as if you 
		had entered A: after personally observing that the number 
		was busy on the first dialing attempt. Using the colon 
		in the Dial command is a step saver.   
   
   

Dialing a Stored           A telephone number that you have stored in the   
Number                     MT1432BA's number memory may be automatically 
			   dialed by entering ATNn where N  n = 0, 1, 2, 
			   3, 4, 5, 6, 7, 8  or 9. For example, a number 
			   stored at N3 would be dialed by entering   
			   ATN3 and RETURN. Do not include the letter D 
			   in this command, or the stored number will be 
			   erased (also see Section 4.4.3., on Phone 
			   Number Memory Commands).   


DTR                        An alternate method of causing the    
Dialing                    MT1432BA to automatically dial is DTR Dialing.  
			   Data Terminal Ready (DTR) is a signal that 
$D                         comes into the modem from the terminal or 
			   computer to which it is connected, on pin   
		   20 of the RS232C interface.  In DTR dialing, the 
		   modem automatically dials a stored number as soon as it   
		   receives a high DTR Signal.  The DTR dialing method 
		   is popular in synchronous applications.  To activate 
		   DTR Dialing, enter AT$D1 and hit RETURN.  The modem 
		   dials the phone number stored in the N0 location of 
		   memory when it receives a high DTR signal.  DTR must 
		   remain high for the duration of the call, until 
		   disconnect.  To deactivate DTR dialing, enter AT$D0 
		   and hit RETURN.    
	
	Note when using DTR Dialing in a synchronous application, 
	be sure DIP-Switch #8 is in the UP position to disable V.25bis 
	Command mode.   
   
   
   
Voice/Data                 Another alternate method of causing the    
Dial                       MT1432BA to automatically dial is Voice/Data 
			   Dialing.  With Voice/Data Dialing, the modem    
$VD                        automatically dials the phone number stored 
			   in the N1 position of memory whenever the   
			   Voice/Data switch is toggled.  To enable 
			   Voice/Data Dialing, enter the command AT$VD1 
	     and hit RETURN.  To disable Voice/Data Dialing, enter the 
	     command AT$VD0 and hit RETURN.            
			   

MI/MIC                      The MT1432BA is available with a modified    
Dialing                     dial-up phone line interface, called the "
			    MI/MIC" option.  This option is used in    
$MI                         applications where the modem's dialing 
			    capability is not used, and dialing is done 
			    by an external device (such as an 801 dialer, 
			    a computer, or a PBX/CBX systerm dialer). To 
			    activate MI/MIC option you must first move 
			    the MI/MIC jumper plugs as described in    
			    Chapter 8.  The command $MI, then controls 
			    this function.  AT$MI1 enables MI/MIC operation   
			    and AT$MI0 disables it.   
			    With the MI/MIC option enabled, the MT1432BA's 
		   A and A1 output leads of the telephone line interface 
		   are replaced with MI and MIC imput leads.  (Tip and ring 
		   remain unaffected.)  When MI and MIC are connected 
		   together, the modem  goes off-hook in the originate 
		   mode, for a time period specified by the modem's Abort 
		   Timer (S-Register S7).  The default setting for the 
		   Abort Timer is 30 seconds, but can be set to any value 
		   from 1 second up to 255 seconds.  A 30 second Abort 
		   Timer means that if the modem does not detect a carrier 
		   tone within 30 seconds after it goes off-hook, it 
		   disconnects.   
	   
4.4.2    Dial Modifier Commands   
There are several command characters that can be included within a 
dialing command (following the letter D), called "Dial Modifiers". 
They have various functions, including the selection of Pulse or 
Tone Dialing, pauses in the dial sequence, automatic redials if 
a number is busy, and reverting to the Command mode or switching 
to the Answer Mode after dialing.   


Pulse or Tone Dial             The MT1432BA dials numbers using either 
			       pulse or tone dialing, or a combination 
    P                          of both methods. Pulse dialing is a method 
			       used by rotary-dial telephones, which 
    T                          involves the timed opening and closing 
			       of line relay.   
	   
		Tone dialing is the method used by pushbutton (touch tone) 
		telephones, and is sometimes referred to as DTMF, or 
		Dual-Tone Multi-Frequency dialing. The method used is 
		selected by including a P for Pulse or a T for Tone in 
		the dialing command, right before the digits you wish 
		to have dialed in that manner. For example, you would 
		pulse-dial the number 555-1212 by entering ATDP5551212 
		and hitting RETURN. You could tone-dial the same number 
		by entering ATDT5551212 and hitting RETURN. If neither 
		Pulse nor Tone dialing is  specified in the dial command, 
		the MT1432BA  uses whatever method used last. If the 
		modem has been reset or just powered up, it uses Pulse 
		dialing, even if  the letter P is not included in your 
		dial command.  Nearly all telephone systems in the 
		U.S. are now compatible with tone dialing. Since that 
		is the faster method, you will probably choose the 
		tone method for your dialing.  An example of combining 
		pulse and tone dialing could involve a PBX system where 
		9 had to be pulse-dialed first, then the rest of the 
		number tone-dialed after pausing for a second dial tone. 
		The number would be dialed by entering ATDP9, T5551212 
		and RETURN. (The comma causes a pause, which we'll 
		explain soon.)   

Set Pulse                  This command sets the time ratios between    
Dial Ratios                the open and closed portions of the dialing            
			   pulse frequencies.  To set the dialing pulse 
			   &P ratio of 60 mSec to 40 mSec, enter AT&P0. 
			   To set a ratio of 67 mSec to 33 mSec, enter 
			   AT&P1.  The factory default is &P0 (refer to 
			   Appendix B).   

Automatic                  You can cause the MT1432BA to pause during    
Pauses in                  the dialing sequence by entering a comma    
			   Dialing character where the pause is desired. 
    ,                      This pause will last two seconds. If a longer 
			   pause is desired, more than one comma may be    
		 entered consecutively, with each comma causing a two second 
		 pause. You also have the option of changing the length 
		 of the pause caused by the comma, from two seconds to 
		 any other value from 0 up to 255 seconds. This is done 
		 by setting S-Register S8 (refer to Chapter 5).  Each 
		 comma in a dialing command counts as one of the sixty 
		 allowed characters.   

Long Space       When two modems are connected in Normal    
Disconnect       mode (i.e. without error correction) there is no 
		 "polite" means of requesting a disconnect.   
		 A link disconnect request packet is sent under    
     Y           reliable connections.  As a result some "garbage" may be 
		 received when a hangup command is issued.   The Y1 
		 command enables the modem to use the break signal 
		 which accomplishes the hangup as an instruction to 
		 shut off its receiver and disconnect (both modems must 
		 have Y1 enabled  for this feature to be effective).  
		 Y0 (factory default) disables this function.   
	   
Wait for New     A W inserted in the dialing command causes    
Dial-Tone       the MT1432BA to wait for another dial tone, and not 
		resume dialing until another dialtone is detected.           
     W          It is not necessary to enter a W at the beginning 
		of the dialing command to wait for a modem dial   
		tone, because the modem will do that first 
		(pause automatically). In order for this command to 
		work, you must select Wait-For-Dial Tone dialing 
		with the X2 or X4 command, so that your modem will 
		be able to detect the dial tone.   

Return to            A semicolon (;), entered as the last character   
Command Mode         of a dialing command causes the MT1432BA    
After Dial           to return to the Command mode immediately    
Command              after executing the command, instead of waiting    
Execution            for a carrier signal and going on line.   
		     For example, entering ATDT5551212; would tone-dial the 
    ;                number, and do nothing afterwards except go back 
		     into Command mode. This can be useful in dialing 
		     applications where modem data transfer   
		     is not desired, such as voice communications, or 
		     in applications involving the use of touch tones 
		     as a data entry method, such as bank-by-phone.   

Reverse the          In certain operations you may need to reverse    
Mode of              the mode of operation for your modem from      
Operation            originate to answer or answer to originate so that it 
		     would answer the phone and go into answer mode. 
    R                 This command turns off the reversing function 
		     with the R0 command and turns it on with the R1 
		     command with the modem in either command mode. If you 
		     want to reverse from the originate mode, use R 
		     (with no number) in the dialing string.   

Flash On Hook        Some switchboard systems react 
		     to a momentary On Hook. An exclamation mark inserted   
     !               in the command causes the modem to "flash" on hook 
		     for a half of a second, just as if you had held the   
		     switch hook button on a telephone set down for a 
		     half second. For example, to flash On Hook after 
		     dialing the number 555-1234 in order to transfer 
		     to Extension #5678, you might enter 
		     ATDT5551234,,!5678.  The commas cause a 4 second 
		     pause (just to be safe).   

"Calling Card"       The MT1432BA has the capability to detect    
  Detect Tones       AT&T  "calling card" tones for the purpose of    
      $              utilizing the user's calling card number to 
		     originate an on-line connection.  An $ symbol   
		     placed in the dialing string causes the modem 
		     to pause and wait for an AT&T "calling card" 
		     or a 1600 Hz tone (prevalent in the United Kingdom).  
	    When the tone is detected, the rest of the dialing string is   
	    processed.  If no tones are detected within the time period 
	    set by S-Register S7 (default 45 seconds), the  modem will 
	    abort by indicating a  NO CARRIER    message.   Hitting any 
	    key also aborts the $ command.     
	   
	    An example of this command:   
	   
   
   
Quiet Answer           The @  command causes the MT1432BA to wait 
		       before processing the next symbol in the   
     @                 dialing string.  The wait is for one or more 
		       ringbacks followed by 5 seconds of silence.     
		       If the time specified by S-Register S7 passes 
		       before the rings and silence, a NO ANSWER (R)   
	   result code is processed. The  @ command is used for accessing 
	   a system that does not provide a dial tone.  For example, 
	   ATDT5551212@6313550  causes the MT1432BA to dial the first 
	   number (555-1212) and wait for the time specified in S7  
	   for at least one ringback and 5 seconds of silence. If a busy   
	   signal is detected, the MT1432BA  hangs up and generates a BUSY 
	   result code. If it does not detect 5 seconds of silence, a 
	   NO ANSWER  result code is generated after hanging up. If 
	   5 seconds of silence is detected, the second number 
	   (631-3550) is then dialed.   
   
   
4.4.3      
Phone Number Memory Commands   

Storing Phone        A telephone number and command line of up    
Numbers              to sixty characters may be stored in the MT1432BA's 
		     number memory. As many as ten of these numbers 
  D...N              may be stored. Each number will be given a name, 
		     using the codes N0, N1, N2 up to N9. A phone number  
		     is stored by entering ATD, then the number as it 
		     would be dialed, along with any  P, T, R, ; or 
		     comma characters, and then entering N  followed by the 
	    number's "name," which would be any number from 0 through 9, 
	    and then hitting RETURN.  For example, the tone-dialed number 
	    1-612-631-3550 would be stored as number N3 by entering   
	    ATDT16126313550N3 and RETURN. The number is not dialed with 
	   this store command. When phone numbers are stored, the entire 
	   command line is also stored so that you can effectively create 
	   a macro for each number. For example, if you know a particular 
	   number needs to have extended result codes, detect busy or 
	   dial tone, error correction, Xon/Xoff flow control, pacing, 
	   and data compression enabled, the command line would be: 
	   ATX4&E1&E5&E13&E15DT16126313550N3. This would store the   
	   entire command at location N3.   

Number Linking            You may command the MT1432BA to dial    
			  another number automatically if the first     
     NN                   number dialed is busy. This would be useful 
			  in a situation where a computer can be accessed   
			  through more than one phone number. This is 
			  called "linking". To link the number in N1 to 
		the number N2, simply enter ATN1N2 and hit RETURN. Several   
		numbers can be linked in the same command. For example, 
		you could link N1 to N2 to N3 to N4 by entering ATN1N2N3N4 
		and RETURN or you could link N1 to N2 and back to N1 and 
		then back to N2 by entering ATN1N2N1N2 and RETURN.   
		The only limit on the number of numbers that can be 
		linked is the 60 characters allowed in a command line. 
		Number linking can not be used with blind dialing, since 
		busy signals would not be detected.  You would have to 
		select the Wait-for-Dial tone dialing method using 
		the X Command in order to use the Number Linking feature.   

Listing Numbers           Telephone numbers that you have stored in the   
Stored in                 MT1432BA's memory may be listed and    
Memory                   displayed with the L command. It will display 
			 all ten stored N numbers in a format like that 
   L                     shown below.  All digits and command letters 
			 will be shown. The number's "name" (0 thru 9) 
			 is shown first, followed by the complete 
			 dialing command and telephone number as originally 
			 entered.  Simply enter ATL and hit RETURN to 
			 display these numbers on your video screen or 
			 printer. An example of an L Command listing 
			 is shown below :   
		
		
		0       T14082345678   
		1       T16125551212;   
		2       P9,T14089876543   
		3       T3738315,12101,16126313550   
		4       T6313551R   
		5   
		6       P9,4258513   
		7                                                 
		8   X4&E1&E5&E13&E15DT16126313550               
		9       T12138880123       
   
   
   
4.4.4     Configuration and Default Storage Commands    

Store Configuration           The MT1432BA can store configuration    
& S-Register                  parameters and S-Register values   
Parameters in                 in its non-volatile read/write Random Access     
Non-Volatile                  Memory(RAM) memory.  The &W command     
Memory                        does this, which prevents any reconfiguration    
  &W                          from being lost on a power-down or Reset 
			      (ATZ) condition. &W0 (or AT&W) causes the 
			      MT1432BA to store your customized AT command 
			      settings and S-Register values in its 
			      nonvolatile  RAM. &W0 also sets the modem so 
			      that it reads your customized settings   
	     stored in nonvolatile RAM when powered down or reset. (The &W0 
	     command only changes the settings stored in nonvolatile 
	     RAM that you specifically intend to alter. All other default 
	     parameters are applicable.)   
	     W1 causes the MT1432BA not to store your customized 
	     settings to nonvolatile RAM so that,after powering down or 
	     resetting the modem, it reads the factory default settings 
	     stored in ROM.    
   
Loading Factory             The &F command provides a choice between    
Defaults                    customized configuration settings in RAM     
&F                          and the factory default configuration settings 
			    in ROM. The &F8 and &F9 commands define the   
			    function of the &F command.    
							
			    The MT1432BA is shipped from the factory with 
			    a pre-configured set of command and S-Register 
			    default settings.  This set of factory defaults 
			    can be recalled by issuing the &F command.  
			    In addition  to being able to recall the 
			    factory-installed defaults, the &F command 
		can also recall those defaults stored under &W0.  This 
		is done using the &F9 command.  If you have stored 
		parameters with the &W0 command and wish these settings 
		to always be used as your defaults, you would enter 
		&F9&W0.To return the &F command to read factory installed   
		defaults, enter &F8&W0.  &F8 is the factory default.                   
		Many datacomm programs, including MultiExpressTM and   
		MultiExpress for WindowsTM, issue the &F command 
		automatically- the &F9 command allows the user to select   
		their own defaults.Note that the &F8/&F9 commands should 
		be used with &W0.   
   
Modem Reset             The Z command can be used to reset the  entire 
			Command Mode buffer and the result is    
     Z                  the same as if you had disconnected, and 
			then reconnected power to the modem. When an ATZ   
			command is executed, the state of the &W command 
			determines where the default values originate. &W0   
			defaults come  from RAM and &W1 defaults come 
			from ROM.   

Unix UUCP               The MT1432BA can be configured in a Unix    
Spoofing                environment that employs ACK flow control    
			as a means of monitoring data integrity. The    
  $SP                   MT1432BA can do "UUCP spoofing", where the modem is 
			able to generate ACKs at the DTE interface. Data 
			is transmitted more time efficiently because 
			the delay of waiting for data to be received, then   
	     for an ACK to be returned at the remote end, is eliminated. 
	     The $SP1 command enables UUCP spoofing and the default command 
	     $SP0 disables UUCP spoofing. 
	     
Async/Sync                   This command can be used to set the on-line    
Mode                         mode to either synchronous or asynchronous.     
Switching                    AT&M0 will set the MT1432BA to Asynchronous 
			     mode, and all communications will be 
  &M                         Asynchronous, in both On-line and Command 
			     modes.  AT&M1 causes the MT1432BA to 
			     communicate asynchronously when in Command 
			     mode and switch to synchronous mode while 
			     on-line. The modem defaults to &M0 
			     (asynchronous communications) on reset or 
			     power-up.   

Synchronous                  The &X command selects the Synchronous    
Transmit Clock               Transmit Clock Source in conjunction with    
Select                       DIP-Switch #11.  DIP-Switch #11 in the UP 
			     position enables External clocking.  DIP-    
  &X                         Switch #11 in the DOWN position enables 
			     Internal clocking (default position).  
			     External clocking is when the DTE provides 
		transmit clocking to the modem on pin 24 of the RS232C  
		interface. &X0 is the default setting, which allows 
		DIP-Switch #11 to control Internal/External Clocking   
		(default Internal). Internal clocking is when the modem 
		provides transmit clock to the DTE on pin 15 of the   
		RS232C/V.24 interface. The &X1 command overrides 
		DIP-Switch #11 and selects External clocking.  If   
		DIP-Switch #11 is UP (External clocking), you can not 
		override Internal clocking.  &X2 enables Slave Clocking.  
		The &X2 Command causes the MT1432BA to generate the 
		transmit clock timing (pin 15) from the receive clock 
		(pin 17) from the DTE (therefore 15 and 17 are the same).  
		In this mode (Slave Clocking), all timing is controlled 
		by the receive clock.    
   
   
4.4.5  Command Response (Result Code) Commands   
   
Echo Command               If the MT1432BA is connected to a full-duplex    
Mode Characters            computer, it may be necessary for the modem to 
			   be configured to echo back characters entered    
      E                    while in the Command mode in order for them to 
			   be displayed. The E command is used to configure 
			   the Command Mode echo, with ATE0 disabling 
			   the echo and ATE1 enabling the echo (default).   

Result Codes               The Q  command enables or disables Result    
Enable/Disable             Codes and the No Response Answer mode of operation    
and No Response            Result Codes may be disabled altogether in 
Answer                     certain applications, such as computer-controlled  
			   auto dialing, using the Q command. ATQ1 disables 
			   Result Code transmissions. ATQ0 (or ATQ) enables 
			   Result Code transmission. Regarding No Response 
			   Answer, you may want the answer mode handled 
			   without responses and echo turned off, but 
			   want the originate mode still intelligent. 
			   This is called the No Response Answer mode.   
			   ATQ2 selects the No Response Answer mode. 
			   If you do not select any mode, the factory 
			   default setting (enable Result Codes) is 
			   automatically selected.   

Result Codes               The MT1432BA gives you a choice between    
("Multi-Tech" or           the Multi-Tech Result Codes, and Result    
"Standard AT")             Codes that more closely match the standard AT 
			   command set responses (see section 4.3).   
      &Q                   AT&Q1 selects AT responses with no 
			   Reliable/Compression modifiers. With this 
			   command, the terse result code for CONNECT 2400 
			   is 10. AT&Q0 selects Multi-Tech responses with 
		  Reliable/Compression modifiers. With this command, the 
		  terse result code for CONNECT 2400 is 9.   

Result Codes               The V command controls whether the    
(Verbose/Terse)            MT1432BA's result codes are displayed as word 
			   ("verbose") or single digit ("terse") messages.     
     V                     For example, if after dialing, no carrier signal 
			   is detected, the resulting message  can be 
			   displayed either as NO CARRIER, or as the digit 
			   3. Entering ATV0 (or ATV)  causes the MT1432BA 
			   to display the Result Codes as digits, while   
	      ATV1  displays them as words. If you do not select a method, 
	      the factory default setting  causes the modem to display 
	      Result Codes as words.   

Result Codes (Basic         The  X Command is used to select    
and Extended) and           one of two possible dialing methods    
Call Progress               ("dumb" or "smart"), and to select various    
Selection                   response combinations related to these    
			    methods. You can choose to have certain    
      X                     responses suppressed, or whether or not 
			    you want speed indications along with the 
			    CONNECT responses. You can also pick and 
		choose certain responses in order to match up with 
		"Standard AT" responses. (Refer to Appendix F for a 
		summary of Result Codes.)  The MT1432BA provides "Basic" 
		and "Extended" Result Code sets. The difference between the   
		two is the Basic set provides one response (CONNECT) 
		to indicate a connection, while the Extended set provides 
		several responses for different speeds (CONNECT, CONNECT 
		2400, CONNECT 4800, CONNECT 9600 and CONNECT14400). When 
		the Extended set is chosen, you also have the option of 
		matching them up with Standard AT 2400 response code sets, 
		by including or not including the BUSY and/or NO DIAL TONE  
		responses while excluding the DIAL TONE response. The X 
		command is used to select which responses are provided.   
		Regarding the MT1432BA's method of dialing, the MT1432BA 
		can detect standard dial tones and busy signals. This 
		capability ("smart dialing") allows the modem to wait 
		for a dial tone, and when one is detected, to begin dialing 
		immediately. The MT1432BA also can detect a distant busy 
		signal, if after dialing, it reaches a busy number. This 
		is useful because it allows the modem to immediately 
		abandon a call, rather than wait 45 seconds for a   
		carrier signal that will never come. S-Register S7 
		defines the wait for carrier time (refer to Chapter 5).   
		The MT1432BA gives you a choice between the wait-for-dial-
		tone ("smart") method we just described, and blind ("dumb") 
		dialing, where instead of detecting actual dial tones, 
		the modem relies on timed  pauses. When the 
		wait-for-dial-tone method is chosen, the busy signal 
		detection capability is also activated. The X command is 
		also used to select which dialing method is used.   
		Five different X commands are available (X0 through X4), 
		with five different affects on the   

MT1432BA's Result Codes.   
		
		X0      Provides the basic (short) result               
			codes and provides "dumb"                                 dial capabilities.   
		X1      Provides the extended result codes              
			and provides "dumb" dial          
			capabilities.   
	The remaining X commands affect Call Progress, and turn on 
	Extended Result Codes.   
		X2      Looks for dial tone only and will not   
			provide a busy response.   
		X3      Looks for busy only and not look for    
			dial tone.   
		X4      Looks for dial tone and for busy.   
	
	The factory default setting is X0, which selects Basic Result 
	Codes and the blind ("dumb") method of dialing.   
   
4.4.6     Phone Line Conditioning Commands   

Guard Tones             The &G command is used to control the presence or 
			absence of guard tones from the transmitter when 
    &G                  in Answer mode, at either 1200 or 2400 bps. Guard 
			tones are used in Europe and other areas for the 
			modem to function in the telephone systems. Guard 
			tones are not used in the United States. &G0 
			(default), turns off CCITT guard tones. &G1 
			turns on 550 Hz guard tones. &G2 turns on 1800   
			Hz guard tones.   

Bell or V.21 Tone       The B command selects the frequency that 
			the modem uses for its answer tone. (The B  answer 
			tone is the tone transmitted by a modem receiving a 
			call to the modem that called it, which initiates 
			the handshaking between the two modems.) At 
			higher speeds (2400 to 28.8 K bps) there is no   
			conflict, because all use CCITT frequencies. At 
			lower speeds (0-1200 bps), in the U.S., some 
			modems use the Bell frequency of 2225 Hz. However, 
			the CCITT specification for V.22 has an answer tone 
			frequency of 2100 Hz. The ATB0 command enables 
			CCITT frequencies including V.21 (300 bps) and 
			V.23 (1200/75 bps). The ATB1 command enables Bell 
			frequencies including Bell 103 (300 bps). The  
			MT1432BA default is ATB0.   

Phone Line           The MT1432BA has an internal on-board,    
Monitoring           speaker which functions like the speaker in a    
Speaker              telephone handset to enable you to monitor phone line 
		     activity. The M command can be used to determine 
		     when the speaker is operational. Entering ATMO disables 
     M               the speaker completely, while ATM1 causes the speaker 
		     to be on only until a carrier signal is detected. ATM2 
		     causes the speaker to remain on at all times. ATM3  
		     causes the speaker to be on during dialing and off 
		     during handshake. ATM1 is the default setting, and 
		     the one that   should be used in most applications.   

Enable or Disable       The MT1432BA has several self-test features   
Recognition             (covered in Chapter 7). The tests are    
of Remote               activated with different U commands, such as    
Digital Loop Signal     ATU1, and so forth. The &T command is a 
			phone line conditioning command that &T enables 
      &T                or disables the modem's ability to recognize the 
			Remote Digital Loop (RDL) test signal.     
			The AT&T4 command lets the MT1432BA respond to a RDL 
			signal, and places itself in digital loop. The 
			AT&T5 command causes the modem to ignore the RDL 
			signal. The factory default is &T5.   

Enable/Disable          This command enables or disables the Trellis    
Trellis Coded           Coded Modulation of the MT1432BA. There is     
Modulation              usually no need to disable (turn-off) Trellis codings 
			except under an unusual line condition called impulse 
			noise.  AT#T0 turns Trellis coding off and AT#T1 
			turns Trelis coding on (factory default).   
		   
		    
Fallback Modes          If line conditions deteriorate, the MT1432BA    
When On-Line            automatically drops its transmission speed 
			("fallback"). The #F command controls the    
     #F                 different ways the MT1432BA falls back. 
			During operation, if the error rate becomes 
			too great, the modem performs a retrain. If 
			after the retrain, the error rate is still too 
			high for 14400 bps operation, the   
			modem initiates a retrain at 4800 bps.   
			If after the first retrain the modem returns on 
			line at 14400 bps, the modem then starts a counter   
			and a timer. If three retrains occur within a 
			two minute period, the modem falls back to 4800 
			bps. Entering AT#F0 (or AT#F) allows no fallback 
			when on-line. AT#F1 allows the MT1432BA to   
			fallback (based on the error rate or if three 
			retrains have occurred within a two minute period) 
			from 14.4K to 12K to 9.6K to 4.8K bps (factory 
			default).  The AT#F2 command enables incremental 
			fallback from 14.4K to 4.8K but also enables fall 
			forward (from 4.8K to 14.4K incrementally).  AT#F2 
			is the factory default       

Auto Speed Detect       The function of the #A command is to detect 
			and select the operational data rates   
			(the "starting" speeds) with which the MT1432BA 
			uses for initial handshake and speed selection.   
     #A                 Remember, this command does not control the 
			originating data rate of the modem (that is done by   
			the Modem Baud Rate command $MBn), but only the 
			Answer mode "starting" speeds. Entering AT#A0 (or  
			AT#A) causes the MT1432BA to operate starting at 
			14400 bps, with incremental fallback to 9600, 
			4800, 2400,1200 and to 300 bps. AT#A1 uses 14400 
			bps only. AT#A2 causes the modem to operate at 
			starting speeds of 14400 bps, with incremental  
			fallback to 9600 and 4800 bps. The AT#A3 command 
			causes the modem to begin operation as a 
			V.22bis modem at 2400 bps, with incremental 
			fallback to 1200  and to 300 bps. AT#A0 is the 
			factory default value.   
   

4.4.7     RS232C Interface Control Commands   

Carrier Detect               The &C command allows you to control the    
Control                      status of the Carrier Detect signal (CD-Pin 8) 
			     on the RS232C line.  You have four choices.     
  &C                         You can force the signal high, or allow it 
			     to act normally, or force the modem to reset 
			     when CD drops, or set it to stay high until 
			     the modem disconnects, go low momentarily, 
			     and then go high again. The last option is 
			     useful with some CBX phone systems and 
			     mainframe front ends, which require CD to act 
			     in this manner. To allow CD to act normally, 
			     enter the command AT&C1 (the factory default 
			     setting). To force CD on, enter AT&C0. To 
			     reset the modem to its current parameters 
			     when CD drops, enter AT&C4. o set up CD so 
			     that it drops for one second on disconnect 
			     and then comes up again, enter AT&C2. (If 
			     you want the drop time to be something other 
			     than one second, use S-Register S24 to change 
			     this value. Refer to the Chapter 5 
			     instructions for S24. 

Data Terminal                Data Terminal Ready (DTR) on pin 20 of the    
Ready Control                RS232C interface is required in order for the 
			     MT1432BA to operate. A high DTR signal    
    &D                       tells the modem that the device to which it 
			     is connected is active, or "ready" to 
			     communicate through the modem. If the signal 
			     is not being provided on the RS232C interface, 
			     you can force DTR high with DIP-Switch #1 
			     (Chapter 8). DTR has some other MT1432BA 
			     functions. DTR can be used to trigger a  
			     dialing sequence, called DTR Dialing. The 
			     condition of DTR can also be used to cause the 
			     modem to reset to its default parameters,   
	   just as if  you had given the modem an ATZ command. To do this, 
	   enter the command AT&D3 and hit RETURN. The modem will now 
	   reset itself whenever DTR is dropped from On to Off, and will 
	   also go on-hook (hang up) if it is on-line. Entering AT&D0 or 
	   AT&D causes the MT1432BA to ignore DTR. Entering AT&D1 causes 
	   the modem to go on-hook (hang up) with loss of  DTR. The 
	   modem enters Command mode when DTR goes high again. Auto-answer 
	   is disabled while DTR is low. Entering AT&D2 causes the modem 
	   to go on hook with loss of DTR. The modem enters command mode 
	   when DTR goes high again.   

CTS Control               The &R command allows you to control the Clear to 
			  Send signal (CTS-Pin 5) on the RS232C   
   &R                     interface. You have three choices. You can force 
			  the CTS signal high, allow it to act normally, or   
			  set it to stay high hntil the modem disconnects, 
			  go low momentarily, and then go high again. The 
			  last option is useful with some CBX phone 
			  systems and mainframe front ends, which require 
			  CTS to act in this manner.  To allow CTS to act 
			  normally, enter the command AT&R0. To 
	    force CTS on, enter the command AT&R1 (this is the factory 
	    default setting). When the modem goes on-line, CTS still 
	    provides flow control. To set up CTS so that it drops for 
	    one second on disconnect and then comes up again, enter the 
	    command AT&R2. (If you want the drop time to be something 
	    other than one second, use S-Register S24 to change this value. 
	    Refer to Chapter 5).   

Data Set Ready             The &S command allows you to control the    
Control                    status of the Data Set Ready signal 
			   (DSR - pin 6) on the RS232C interface. You have     
  &S                       three choices. You can force the signal high, 
			   allow it to act normally, or set it  to stay 
			   high until the  modem disconnects, go low 
			   momentarily, and then go high again. The last 
			   option is useful with some CBX phone systems 
			   and mainframe front ends, which require DSR 
			   to act in this manner. To allow DSR to act 
			   normally, enter the command AT&S1 (the default 
			   setting). To force DSR on, enter the command 
			   AT&S0. To set up DSR so that it drops for one 
			   second on disconnect and then comes up   
	  again, enter AT&S2. (If you want the drop time to be something 
	  other than one second, use S-Register S24 to change this value. 
	  Refer to Chapter 5.)    

CTS/RTS                    In typical operation, Clear to Send will follow   
Interaction Control        Request to Send when the modem is on-line. 
			   In other words, if RTS goes off, CTS will go     
  &RF                      off in response. The &RF0  command enables 
			   CTS to follow RTS. In some applications, 
			   however,it  may be necessary for CTS to 
			   operate independent of RTS. &RF1 allows CTS 
			   to operate independently regardless of the 
			   state of RTS, and  is the factory default. 
			   If this is the case, refer to the &R command 
			   for control of the Clear to Send signal.   

DSR/CD                     In typical applications, Data Set Ready (DSR)    
Interaction Control        will follow Carrier Detect (CD). &SF0 
			   enables DSR to follow CD, and is the   
			   factory default.     
  &SF                      &SF1 enables DSR to operate independent of CD.   
			   If this  is the case, refer to the &S command   
			   for control of the Data Set Ready signal.   
   

4.4.8    Error Correction Commands   

You can use AT commands to place your MT1432BA one of three 
V.42 (error correction) modes of   
operation. These are the Normal, Auto-Reliable, and Reliable modes.    
   
Normal Mode                In Normal mode of operation, the    
			   MT1432BA's V.42 error correction capabilities    
     &E0                   are disabled, and the modem  functions as 
			   a non-error-correcting modem.    
   
Auto-Reliable Mode         In Auto-Reliable mode during the 
			   handshaking procedures at the start of    
     &E1                   the on-line connection, the MT1432BA 
			   automatically determines whether or not the   
			   modem with which it is communicating is 
			   using V.42 error correction. If the MT1432BA 
			   determines that the other modem is using V.42, 
			   it  switches itself into Reliable (V.42) 
		mode and its error-correction capability is enabled. If 
		it is determined that the other modem is not using V.42, 
		the MT1432BA remains in Normal mode, without error 
		correction. The default setting is Auto-Reliable mode 
		(&E1). The method the MT1432BA uses to determine if 
		the modem it calls is a V.42 modem involves the use of 
		a "Link Request".   When the MT1432BA is in Auto-Reliable 
		mode and originates a call, it goes through normal   
		handshaking procedures just like any dial-up modem. 
		After establishing the on-line connection, the MT1432BA 
		transmits a Link Request message to the answering 
		modem. (The Link Request message is generally about 33 
		coded characters.) If the answering modem replies 
		with an appropriate V.42 acknowledgment response, the 
		MT1432BA  switches into Reliable mode. Otherwise it stays 
		in Normal mode. This V.42 Link Request handshaking 
		procedure generally takes about five seconds. When operating 
		in V.42 Reliable mode, the MT1432BA uses its memory, 
		or buffer, to store data as it is received. During periods 
		of error-caused retransmissions or compression slowdowns, 
		this buffer may fill up. To prevent buffer overflow and 
		subsequent loss of data, the modem uses "flow control" 
		to signal the computer attached to its RS232C port that 
		the modem buffer is close to being full. This causes 
		the computer to pause in its data transmission until 
		the modem is able to empty its buffer sufficiently to 
		accept more data, at which time the modem signals the 
		computer that it may resume transmission. (Flow Control 
		is discussed in section 4.4.9).   

Reliable Mode              In Reliable mode, the MT1432BA uses its    
			   V.42 error correction capabilities during all    
     &E2                   transmissions, and must be connected to another 
			   modem with a similar protocol activated (MNP or   
			   LAP-M). 

V.42 Mode Select           The V.42 standard implements both MNP 
			   Class 3 & 4 and LAP-M error correction    
     #L                    methods. The V.42 Mode Select command (#L) 
			   selects which type of error correction (MNP or   
			   LAP-M) your MT1432BA  uses for transmissions.    
			   The various #L command options are as follows.   

#L0 Command                The #L0 Command allows a pair of modems to 
			   negotiate which V.42 mode (MNP or   
			   LAP-M) will be used in their transmissions.   
		
		Originate Mode                          
		     a.      If both modems have AP-M capability, the           
			     modems  use LAP-M  mode.   
		     b.      If one or both modems do not have LAP-M         
			     capability and both have MNP, the                        
			     modems use the MNP mode.        
	   
		Answer Mode   
		      a.      The answering modem  responds to either         
			      an MNP Link Request or LAP-M Originator                 
			      Detection Pattern (ODP) signal depending               
			      on which the originating modem issues.   

#L1 Command         The #L1 Command sets your modem to MNP error 
		    correction and disables LAP-M. This command is 
		    for Originate mode only.  In Answer mode, the modem 
		    still accepts MNP or LAP-M.    

#L2 Command         The #L2 Command sets your modem to LAP-M error 
		    correction, and disables MNP. This command is for 
		    Originate mode only. Answer mode still accepts MNP 
		    or LAP-M.   

#L3 Command         In the prior  commands, the modems use a two phase 
		    process to establish a V.42 connection (detection 
		    to establish whether the remote modem is also 
		    error correcting, and then protocol establishment 
		    to determine parameters and to establish the error 
		    correction connection). If you know that the other 
		    modem is a V.42 error correcting modem, and you 
		    wish to use LAP-M, the #L3 command disables   
		    the detection phase and goes directly to protocol 
		    establishment. Both modems must have #L3 in effect.   
   
Auto-Reliable       In Auto-Reliable mode, the modem is given    
Buffering           four seconds to establish a Reliable connection. After 
		    this four-second period, the    
   $A               modem drops to Normal mode. Any data which is 
		    received during this period is typically discarded. 
		    The $A command can be used to cause the modem to 
		    buffer (save) data that is received during this 
		    Auto-Reliable time-out period. This data will then be output by the modem after the CONNECT message.   

       AT$A0 = Discard data received                   
	       during auto-reliable time period.    
       AT$A1 = Buffer data received during auto-               
	       reliable time period.    
		
	    The factory default is $A0.   

Enable/Disable              In Auto-Reliable mode, the modem is given    
Auto-Reliable               fourseconds to establish a Reliable connection.     
Fallback Character          Ifa single CARRIAGE RETURN is received 
			    from the remote modem during this four     
    $F                      second period, the Auto-Reliable modem  assumes 
			    that the remote modem is not in Reliable mode   
			    and  drops to Normal mode. The CARRIAGE RETURN 
			    is the only character which causes the modem to   
			    drop to Normal mode. Any other character will 
			    either be buffered or discarded.   
			    The $F command can be used to disable this 
			    fallback-to-Normal-due-to-CARRIAGE-RETURN   
			    feature. The Auto-Reliable fallback character 
			    ($F) and Auto Reliable buffering ($A) commands 
			    can be used together to cause the modem to 
			    buffer all data received up until the CARRIAGE 
			    RETURN, and then drop to Normal mode. All data 
			    received will then be output following the 
			    CONNECT message.   
		AT$F0 =         Do not fall back to Normal if   
				CARRIAGE RETURN received.   
		AT$F1 =         Fall back to Normal mode if     
				CARRIAGE RETURN received.   
				The factory default is $F1.   
Retransmit Count           If errors are received during a Reliable 
			   connection, the modem  re-sends the block of    
      $R                   data which contained an error. With the $R0 
			   command, if another error occurs, the block will 
			   be re-sent again. The modem counts the number of 
			   times that a data block is re-sent. If the same 
			   block of data is resent 12 times and still has not 
			   been received properly, the modem assumes that the 
			   transmission line is unsuitable for transmission,   
			   and abort the connection.   
			   This retransmit counter is disabled by the $R1 
			   command. When the retransmit counter is disabled,   
			   the modem keeps trying to send data and will not 
			   abort, no matter how many times the same block is 
			   resent.   
			   AT$R0 = Disconnect if retransmit count is               
				   exceeded.   
			   AT$R1 = Do not disconnect due to retransmits.   
			   
			   The factory default setting is $R0.   

V.42 Error                 At 300 bps, error correction is not typically     
Correction/300bps          used. $E1 lets the MT1432BA function at 300 bps 
			   in either Normal (&E0), Auto-Reliable (&E1)     
      $E                   or Reliable (&E2) mode. $E0, which is the 
			   MT1432BA's default, disables 300 bps/V.42 error   
			   correction altogether.   
	   
				   
   
4.4.9    Flow Control Commands   
Flow control refers to the techniques used by computer devices to stop 
and restart the flow of data to and from each other. Flow control is 
necessary so that a device does not receive more data than it can handle. In   
the case of the MT1432BA, there is a need for flow control in both 
directions. As illustrated on the next page, flow control for data passing 
from your computer to the modem is called Modem-Initiated Flow   
Control and flow control for data passing from the modem to your 
computer is called Computer/Terminal-Initiated Pacing.   
The MT1432BA supports both hardware and software Modem Initiated 
Flow Control. On the Computer/Terminal-Initiated Pacing side, it supports 
hardware and software flow control, and a special version used by 
Hewlett-Packard compatible systems called ENQ/ACK Pacing. The MT1432BA 
allows hardware and software pacing to be passed through the modem to the 
other end of the link so that your computer or terminal can control data 
start/stop activity through your modem. This is called Xon/Xoff Pass-  
Through.  To state  it simply, "Flow Control" is something the modem 
does to the computer, while "Pacing" is something the computer does to 
the modem.   
   
   
Hardware Flow        With Hardware Flow Control, the modem uses its RS232C   
Control              interface to control the flow of data from the computer 
		     or terminal to which it is attached. The CTS (Clear to 
  &E4                Send) signal on Pin 5 of the RS232C interface is brought   
		     low to stop the flow of data, and is brought high to 
		     restart it. When you select Hardware Flow Control as   
		     your Modem Initiated Flow Control method, you will also 
		     be selecting it for Pacing.    
							
		     The difference between the two, however, is that 
		     Modem-Initiated Flow Control uses the Pin 5 CTS output 
		     signal, while Pacing uses the Pin 4 RTS input signal.    
		   
		     Modem commands are used to select the method of flow 
		     control used by the MT1432BA when its error correction 
		     capabilities are used. These commands are covered in 
		     Section 4.4.9. If neither method is selected, the modem  
		     defaults to no flow control (&E3).   
   
Xon/Xoff Flow        Xon/Xoff is the most commonly used method of flow    
Control              control. Under this method, control characters known 
		     as "Xon" and "Xoff" are inserted by the modem into the 
   &E%               data to start and stop the flow of data from the 
		     computer or terminal to which the modem is attached.  
		     Xoff, which is a Control-S, stops the flow of data, and 
		     Xon, which is a Control-Q, restarts it. With regard to 
		     Binary Data, Xon/Xoff flow control is not recommended 
		     because an Xoff character may be part of the data and 
		     would trigger an Xoff of the modem or software package, 
		     which would halt data flow.   

Xon/Xoff             So far, you have had three choices to make regarding  
Pass-Through         pacing:   
	&E7     1.      You can set the modem to respond to Xon/Xoff pacing.   
		2.      You can set the modem to respond to RTS pacing.   
		3.      You can set the modem to ignore pacing completely.   
	
		     Well, we're not done with pacing yet. There's another 
		     choice you can make (which actually can apply to both 
		     pacing and modem-initiated flow control, although it 
		     applies mainly to pacing) and that is something called 
		     Xon/Xoff Pass-Through. This means that if your modem is 
		     set to respond to Xon/Xoff commands, you can have the 
		     modem do one of the following:   
	
	1.        The modem responds to the Xon and Xoffpacing commands 
		  while at the same time allowing these commands to pass                 
		  through the modem and on to the remote location. We call 
		  this "Respond, Pass-Through".  
	   
	2.        The modem responds to Xon/Xoff pacing, but does not allow 
		  the pacing signals to pass through the modem and on to 
		  the remote location. We call this "Respond, No Pass-
		  Through". When Xon and Xoff commands are allowed to pass 
		  through the modem, the computer or terminal at the remote 
		  site will receive these commands, and depending on how it 
		  is configured, the computer or terminal may respond to 
		  them also. When two MT1432BAs are connected in Normal mode 
		  (not using error correction), Xon/Xoff can be used to 
		  control the flow of data between the modems. Flow Control 
		  can be turned on or off with the Normal Mode Modem Flow 
		  Control commands. When the modems are connected in Reliable 
		  mode, a different method of modem Flow Control is used, 
		  and the commands for Normal Mode Modem Flow Control are 
		  ignored.   
		  When you are using Speed Conversion in Normal Mode, you 
		  must activate the modem's Normal Mode Modem Flow Control. 
		  (Speed Conversion is explained in Section 4.4.11.)   

Send Xon/Xoff     The #X phone interface command allows the  MT1432BA
Characters        to send either a single or multiple Xoff characters at 
		  the modem's buffer full level. When the MT1432BA's buffer 
   #X             reaches it's "buffer full" level, the next character 
		  received causes another Xoff to be sent for for every 
		  character subsequently received by the MT1432BA.   
	   
		  The AT#X0 command ( factory default setting) causes one 
		  Xoff to be sent until the buffer reaches the Xon level.  
		  The AT#X1 command causes an Xoff to be sent for every 
		  character received after the modem reaches its buffer full 
		  level. 

Hewlett-Packard   If the MT1432BA is being used with Hewlett Packard  
ENQ/ACK Pacing    (or similar) equipment that employs ENQ/ACK pacing, the 
		  modem can be configured to respond to ENQ/ACK commands, 
    &E9           making it compatible with HP systems. Doing so does not 
		  affect any other flow control or pacing already configured 
		  in the modem.   
		  When configured for ENQ/ACK, the ENQ (Control-E) and 
		  ACK (Control-F) signals from the HP equipment will be 
		  accepted and responded to according to Hewlett-Packard 
		  protocol.   

Normal Mode       When two MT1432BA's are connected in Normal mode   
Modem Flow        (not using error correction), Xon/Xoff can be used to   
Control On        to control the flow of data between the modems. Flow 
		  Control can be turned on or off with the Normal Mode    
     &E11         Modem Flow Control commands. When the modems are connected 
		  in Reliable mode, a different method of modem flow control 
		  is used, and the commands for Normal Mode Modem Flow 
		  Control are ignored.   
		  When you are using Speed Conversion in Normal Mode, you 
		  must activate the modem's Normal Mode Modem Flow Control. 
		  (Speed Conversion is explained in Section 4.4.11.)   

Terminal/Computer       As mentioned earlier, the MT1432BA can iniate flow
Initiated Pacing        control by issuing Xon/Xoff commands or toggling the 
			CTS signal on the RS232C interface. The modem can 
			also be configured to react to similar commands and  
     &E13               signals from the computer or terminal to which it is 
			attached via the RS232C interface.   
			We refer to the computer or terminal initiated flow 
			control as Pacing. When the modem is set for Pacing 
			On, the modem will respond to the terminal or 
			computer pacing. When the modem is set for Pacing Off, 
			it will ignore pacing.   
   
			In order for the MT1432BA to be set for Pacing On, a 
			modem-initiated method of flow control must be 
			previously selected. Once this is done, the MT1432BA 
			will respond to either Xon/Xoff commands, or to the 
			toggling of the RTS (Request to Send) signal on Pin 4 
			of the RS232C interface, depending on what you 
			selected earlier as your Modem-Initiated Flow Control 
			method. 

Maximum                 The maximum size of Reliable mode data blocks can be   
Block Size              controlled with the &BS command. MNP 3 sends blocks 
			of 1 to 64  characters. MNP  4 and 5 typically send    
     &BS                blocks of 1 to 256 characters and LAP-M typically 
			send 128 characters. For MNP Classes 4 and 5/LAP-M, 
			reducing the block size to 64 characters may give a 
			smoother flow of data, and better throughput on noisy 
			phone lines. Using smaller block sizes over good 
			phone lines may cause a slight loss in throughput 
			(speed).   
			AT&BS0 = Maximum transmit block size of 64 characters   
			AT&BS1 = Maximum transmit block size of 128 characters   
			(LAP-M) 256 characters (MNP)        
				  
			The factory default setting is &BS1.   

Asynchronous            The MT1432BA has an 11-bit capacity when operating   
Word Length             asynchronously. The $EB  command selects between    
Selection               11-bit and 10-bit operation. AT$EB1 enables the modem 
			to function in an 11-bit format (one start bit, eight    
     $EB                data bits, one parity bit and one stop bit). $EB0 is   
			the modem's default setting and enables the MT1432BA 
			to operate in 10-bit format (one start bit, seven   
			data bits, one parity bit and one stop bit). $EB is 
			functional in  both command and on-line mode. $EB0    
			automatically detects parity when any AT command is 
			issued.    
Parity Selection        The #P command enables the setting of parity. 
			AT#P0 selects no parity. AT#P1 selects odd parity.    
     #P                 AT#P2 selects even parity and is the default value.    
   
4.4.10    Compression, Error Correction, Flow Control, Pass-Through and   
	  Pacing Commands   

The MT1432BA has a variety of commands to control its error 
correction and data compression options. These additional commands are 
listed below. (Remember to precede each command with the AT characters.)   

Normal/Auto-Reliable/Reliable Mode Commands:   
	&E0     =       Normal Mode   
	&E1     =       Auto-Reliable Mode*   
	&E2     =       Reliable Mode    
Modem-Initiated Flow Control Commands:   
	&E3     =       Disables flow control (no flow control)   
	&E4     =       Hardware flow control (CTS on/off and RTS on/off)*   
	&E5     =       Xon/Xoff flow control   
Xon/Xoff Pass-Through Commands:   
	&E6     =       Modem responds to Xon/Xoff characters, but does    
			not allow Xon/Xoff characters to pass through to    
			remote site.*   
	&E7     =       Modem responds to Xon/Xoff characters, and allows    
			them to pass through to remote site.   
	#X0     =       Selects single Xoff character until Xon level 
			returns*   
	#X1     =       Selects multiple Xoff characters after buffer 
			levels is full.   
Enq/Ack Pacing Commands:   
	&E8     =       Enq/Ack method of pacing off*   
	&E9     =       Enq/Ack method of pacing on   
Normal Mode Modem Flow Control Commands:   
	&E10    =       Normal Mode Modem Flow Control off*   
	&E11    =       Normal Mode Modem Flow Control 
			(Xon/Xoff) on   
Computer-or Terminal-Initiated Flow Control (Pacing) Commands:   
	&E12    =       Pacing off*   
	&E13    =       Pacing on (either RTS on/off or Xon/Xoff depending    
			on the setting of &E4 or &E5).*   
Data Compression Commands:   
	&E14    =       Data Compression disabled   
	&E15    =       Data Compression enabled*   
*Factory Default setting    
   
4.4.11    Speed Conversion Commands   
Speed conversion is a necessary part of data compression since data 
must be presented to the modem faster than it can handle data, if data 
compression is to be effective. Speed conversion allows the MT1432BA to 
communicate at one speed over the phone line, and at another speed at the 
RS232C interface. The speed (also referred to as "data rate" or "baud rate") 
can be fixed at the RS232 interface independently of the baud rate of the 
on-line transmissions.In addition to data compression, another popular 
application for speed conversion involves an auto-answer MT1432BA connected 
to a computer that does not have autobaud capability. This means that the  
computer must be set at a fixed baud rate, regardless of whether the modem 
is communicating over the phone line at 300, 1200, 2400, 9600 or 14,400 bps. 
In this application, speed conversion allows the modem to match its speed to 
that of the calling modem, while at the same time communicating with the 
attached computer through its RS232C port at a fixed baud rate, which can be 
preselected at 300, 1200, 2400, 4800, 9600, 19,200, 38,400 or 57,600 bps.   

Speed Conversion        When using speed conversion, you must set the modem
			so that it does not adjust its speed at the RS232C  
      $BA               serial port, even if the modem does adjust its data 
			rate. To turn Speed Conversion ON, enter the command 
			AT$BA0. To turn Speed Conversion OFF, enter AT$BA1 
			and hit RETURN. The modem will now match its RS232C 
			speed to that of the computer, and will adjust its 
			speed to any changes in the computer's speed in   
			Originate mode, or to the speed of the originating 
			modem in Answer mode. The speed at which the modem 
			communicates over the phone line will always be the 
			same as the speed at which it communicates via its   
			RS232C serial port.   

Modem Baud Rate         The $MB command presets the MT1432BA's transmission 
			baud rate for originate operations, (i.e .,the speed 
			of the modem's transmissions over the telephone   
      $MB               lines when originating a call). With speed 
			conversion, this transmission speed can be a 
			different baud rate than the serial port speed.   
			When the MT1432BA receives (answers) a call from 
			another modem, it  automatically switches its   
			phone line transmission speed to match the calling 
			modem. However, if the MT1432BA originates a call to   
			another modem that is unable to connect at the baud 
			rate of the MT1432BA, it  automatically drops to a 
			lower baud rate in an attempt to match the speed of 
			that modem. For example, if the MT1432BA is set for   
			14400 baud and calls another modem that has a top 
			speed of 2400 baud, it drops to 2400 baud. The 
			command to set the Modem Baud Rate is AT$MBn, where 
			n can be 75 (in CCITT V.23 mode) 300,1200, 2400, 
			4800, 9600 or 14400 as listed below:   
		
		AT$MB75         =       CCITT V.23   
		AT$MB300        =       300 bps   
		AT$MB1200       =       1200 bps   
		AT$MB2400       =       2400 bps   
		AT$MB4800       =       4800 bps   
		AT$MB9600       =       9600 bps   
		AT$MB14400      =       14400 bps   
		   
		The factory default is 14400 bps.   
	   
Serial Port Baud       The $SB command presets the speed of the MT1432BA's  
Rate                   serial (RS232C) port, in both Originate and Answer 
		       modes. Speed conversion allows you to set this serial   
     $SB               port baud rate at a fixed speed of up to 57,600 bps,   
		       regardless of the modem's transmission speed setting.   
		       In order for this command to be effective, the modem's 
		       Speed Conversion feature must first be turned off with 
		       the $BA command. When Baud Adjust is on, the MT1432BA 
		       automatically adjusts its serial port baud rate to 
		       match the speed of the computer or terminal it is 
		       connected to, as soon as it receives its first AT 
		       command. However, in many applications, such as 
		       automatic answer, the modem may not receive AT 
		       commands, in which case it is very useful to be able 
		       to preset the serial port baud rate with this $SB 
		       command.   
		       In addition to setting the MT1432BA's serial port 
		       speed, this command also sets the speed at which   
		       the modem issues Command mode responses.
		       The MT1432BA will accept AT commands at any speed, 
		       regardless of the speed preset by the $SB command. If 
		       the modem receives such a command at a speed that is 
		       different than the preset speed, the modem switches 
		       its serial port baud rate to match the new AT command 
		       speed, although the baud rate value stored by the $SB 
		       command remains the same. This provides you with a 
		       convenient way to switch the serial port speed, and 
		       still make it easy to go back to the original speed 
		       automatically the next time the modem is powered up 
		       or reset with an ATZ command. The command to set the 
		       Serial Port Baud Rate is AT$SBn, where n can be 300, 
		       1200, 2400, 4800, 9600, 19,200, 38,400 or 57,600 bps 
		       as listed below:   
		AT$SB300        =       300 bps   
		AT$SB1200       =       1200 bps   
		AT$SB2400       =       2400 bps   
		AT$SB4800       =       4800 bps   
		AT$SB9600       =       9600 bps   
		AT$SB19200      =       19,200 bps   
		AT$SB38400      =       38,400 bps   
		AT$SB57600      =       57,600 bps   
			   
		The factory default is 57,600 bps.   
   
   
   
   
   
   
   
*Some serial ports, particularly those in older PC-compatible 
computers, may limit the performance of ahigher speed modem like the 
MT1432BA.  The limiting factor is a circuit called a Universal Asynchronous   
Receiver/Transmitter, or UART.  All data from your modem flows through it.  
8250, 16450, and 16550 are UARTs typically used in PC-compatible computers.  
The 8250 is unreliable above 9,600 bps and the 16450 is unreliable above 
19,200 bps.  The 16550 UART, however, is reliable to at least 115,200 bps. 
With   V.42bis  data compression enabled, the MT1432BA can achieve 
throughputs approaching 57.6K (depending on line quality and file content).  
If you presently do not have a 16550 UART in your PC, we recommend that it 
be replaced with one.  An alternative too, is to consider replacing your 
slow serial card with a Multi-Tech high speed Intelligent Serial Interface 
(ISI) card.  It comes in two-port and eight-port versions for DOS/Windows 
and UNIX systems, and includes a 32 K buffer that eliminates data loss even 
at high speeds.  See your dealer for details.   
   
   
4.4.12    Immediate Action Commands   
Help Screens         The Help command is designed to give you short      
     $H              explanations on how to use each MT1432BA command. The 
		     Help command can be quite useful if your manual is not 
		     handy and you are in the middle of a communications 
		     session. Although the explanations are quite abbreviated 
		     compared to those in this manual, they should prove to 
		     be helpful reminders when needed.   
		     At the time of this writing, we have three screens of 
		     Help information (Screen #1, #2 and #3), and more 
		     screens may be added in the future. The Help commands 
		     are structured so that you can call up one of three Help 
		     screens, as follows:   
			
			AT$H1 = Help Screen #1   
			AT$H2 = Help Screen #2   
			AT$H3 = Help Screen #3   

Inquiry for          Some systems or software packages automatically   
Product Code         check the "identification" of the modem with which 
		     they are communicating, by using the I command.     
     I               This "read" command lets the software determine the 
		     type of modem  with which it is communicating.   
		     When ATI or ATI0 is entered, the MT1432BA responds with 
		     247. When ATI1 is entered, the modem responds with a 
		     three-digit code indicating the firmware version number. 
		     When  ATI2 is entered, the modem responds with MT1432BA.   

Listing Current      The L5 and L7 commands list the current operating   
Operating            parameters of your modem. This information can be   
Parameters           very useful when you are changing communications 
		     software or when you are changing modem default 
     L5              settings.   
		     The command to list the MT1432BA's current operating 
		     parameters is ATL5 for the basic parameters. The    
     L7              ATL7 command will list additional parameters on the 
		     MT1432BA.    


Listing S-Register      The L6 command lists the current values stored in   
Values                  the modem's S-Register. This information can be 
			very useful if you wish to change S-Register values.   
     L6                 (Refer to Chapter 5 for more information on 
			S-Registers). 
			
			Listing On-Line The L8 command displays the current 
			Diagnostics on-line CONNECT status of the MT1432BA.  
    L8                  This display can be printed and used as a modem 
			status report or as diagnostic information (such as 
			when calling Tech Support).This report is given only 
			when on-line.  To activate this command first type 
			+++AT<CR>(on-line escape command while maintaing 
			command mode), then type ATL8.  What then displays 
			on your monitor is your modem's current on-line 
			condition (e.g., Link Type, Line Speed, Serial Speed, 
			Type of Error Correction/Data Compression, Number of          
			past Retrains,etc.).    
				   
			An example of L8 listing is shown below:   
	   
	      ATL8   
	******  ONLINE DIAGNOSTICS        ******   
	LINK TYPE               V.32bis   
	LINE SPEED              14400   
	SERIAL SPEED            57600   
	ERROR CNTRL/COMPRESS    LAPM COMPRESSED   
	FALL BACK/FORWARD       LOCALLY ENABLED   
	LINE TYPE               DIAL UP   
	DATA FORMAT             ASYNCHRONOUS   
	   
	LINE QUALITY            001    0=EXCELLENT, 8=FAIR,  16=BAD   
	RECV. SIGNAL LEVEL      -016.5  dBM   
	TRANS SIGNAL LEVEL      -013 dBM   
	NUMBER OF RETRAINS      000   
	ROUND TRIP DELAY        000 ms   (MEANINGFUL IN V32 MODE ONLY)   
   
Off Hook                You can make the MT1432BA hang up (go On Hook).  
			ATH1<RETURN> brings the line Off Hook, just as ]
			if you picked up  the telephone  set.  You can   
     H                  hang up by entering ATH0 or ATH (the default is 0 
			when no number is   entered).     
   
Escape Sequences-       It is possible to cause the MT1432BA to enter   
Entering Command        Command Mode after the modem has gone on-   
Mode While Still        line with a remote modem, without disconnecting   
On-Line                 the call.  This is done by entering an Escape Code. 
			The default Escape  Code used by the MT1432BA is    
  +++AT<CR>             three plus signs (+++) followed by the letters A and 
			T,up to sixty command characters (most typically "H", 
			to hang up), and a RETURN.  The number of command 
			characters allowed after +++ AT<CR> , is defined by 
			S-Register S34.  S-Register S34 defaults to ten 
			command characters.   When this is done, the modem 
			escapes to Command Mode, executes the command (if 
			any), and then remain in Command mode. For example, 
			to hang up the modem at the end of a call, enter 
			+++ATH  and hit RETURN. There is no need to 
			incorporate pauses before and after the plus signs, 
			as done in earlier modems.   

BREAK            The MT1432BA provides an alternative Escape method, using 
		 a Break signal as the Escape Code.  The Break signal   
 AT<CR>          allows the start-stop DTE (data terminal equipment) to   
		 signal the modem without loss of character transparency.  
		 With this method, a BREAK signal is used instead of the 
		 three plus signs. The BREAK is followed by the letters A 
		 and T, up to 60 command characters, and RETURN. When this 
		 is done, the modem executes  that command, but remains in 
		 On-Line mode unless the command was to hang up and/or reset 
		 the modem (an H or Z), in which case the modem would be in 
		 the Command Mode after executing that command.      
   
   
Readers interested in further information on the use of BREAK signals 
as escape codes may wish to consult the CCITT X.28 Recommendation.  In the 
"Provisional Recommendation X.28 (Geneva 1977)", information on the topic 
can be found in Section 4.9, entitled "Escape from the data transfer state".  
More   recent editions have been published in 1980, 1984 and 1988.  CCITT 
publications can be obtained from Omnicom, Inc., 112 Park Street SE, Vienna, 
VA 22180, Phone 703/281-1135, FAX 703/281-1505.   
   
Escape Sequence         As mentioned, the default escape sequence    
Options - Entering      setting is for the modem to respond to the       
Command Mode            +++ escape method.  Optional settings are for     
While On-Line           the modem to respond to the Break method, for the 
			modem to respond to either the +++ or the Break    
     %E                 Methods, for the modem to ignore both methods and 
			not escape, for the modem to respond with no "OK" 
			to +++, and for the modem to respond with "OK" to 
			+++. The %E command is used to select these options, 
			as follows:   
   
		%E0     =       Modem Won't Escape   
		%E1     =       +++ AT<CR> Method (default)     
		%E2     =       Break Method   
		%E3     =       Either +++ or Break Methods   
	     *  %E4     =       No "OK" Response to +++    
	     *  %E5     =      "OK" Response to +++   
	   
	*The %E4 and %E5 commands enable or disable an "OK" 
	 response, which is required by some   
	 software packages during an escape sequence.   
   
Force Answer Mode        You can force the MT1432BA into Answer mode 
			 with the modem's A command. Entering ATA when   
     A                   in Command mode immediately brings your modem off
			 -hook, out of Command mode and into On-Line Answer 
			 mode, and causes it to transmit its carrier signal 
			 over the phone line. If no responding carrier tone 
			 is received by your modem within forty-five seconds 
			 (or some other time as determined by S-Register S7), 
			 your modem stops transmitting its tone, hangs up, 
			 and goes back into Command mode.   

Exiting Command          You can bring the MT1432BA out of Command   
Mode, Going              mode and back into On-Line mode by entering     
Back On-Line             ATO (where O is the letter O, not the number 0). In 
			 this case, the O command reverses what was done by    
    O                    entering the Escape Code. The O command will bring 
			 the modem into the same On-Line mode (Originate or 
			 Answer) that it was in prior to going into Command 
			 mode.   

