9-8-93                        USR Modems

     US  Robotics  Dual standard modems will support V32,  the  newer  ones
V32bis. If the USR is a plain HST then the fastest connect will be 2400  as
the  HST  9600 is proprietary protocol. Even when calling a  Dual  you  may
often need to use one of the dial prfeixes to 'force' a connect at 9600  or
higher.
        - - - - - - - - - - - - - - - - - - - - - - - -
              Normal INIT for modems on a PC AT&F&C1&D2
     Sometimes, even though the modem seems to get a good connect  (usually
with  hi-speed modem) it does not actually make the  connection  correctly.
(It  may  be the OTHER end making the error). Often if you use one  of  the
(prefix)  strings to force that connect speed the connection will  be  made
'solid' on both ends.

                 V.32 / V.42bis Dialing Prefixes

     The  normal dial Prefix is ATDT. If the number  is  423-1563 then   it
sends ATDT4231563 to the modem, which then  dials,   and connects. This  is
using  auto-speed  (baud)  negotiation as well   as  negotiating   Protocol
(V.42bis, MNP etc.). Some modems/software you  will call do NOT like  this.
Listed are alternate dial Prefixes you may use.

AT&Q5N1DT           :negotiates SPEED and Protocol (default)
AT&Q6N1DT           :negotiates SPEED only
AT&Q5S37=11N0DT     :*Connect 14400, negotiate Protocol 2
AT&Q6S37=11N0DT     :*Connect 14400 only 2
AT&Q5S37=9N0DT      :*Connect 9600, negotiate Protocol
AT&Q6S37=9N0DT      :*Connect 9600 only
AT&Q5S37=6N0DT      :Connect 2400, negotiate Protocol (HST)
AT&Q6S37=6N0DT      :Connect 2400 only                (HST)
                     * for all V.32 modems
                     2-for V.32bis modems

NOTE 1: The above strings are using buffering which allows the computer  to
have  a higher speed than the modem. If you still have trouble try  &Q0  in
place of &Q6 and set your computer speed the same as the modem speed.

NOTE  2: I discovered when a user couldn't connect to a 300bps modem,  that
if  I  did AT&F (set &C0&D0) before using the dial prefix,  then  it  would
connect. This is worth a try on stubborn 1200bps modems too.

              Connect result messages / modem speed

S95=44   gives  you full result messages with CONNECT  (modem  to  computer
speed).  If  you need CONNECT (modem to  modem) speed the same  as  CARRIER
(modem  to modem) use S95=45. When running a BBS, try  S95=3 and  you  will
get only CONNECT(carrier) message, with \ARQ for error correcting   modems.
Always  set  your  'speed'  in your program  to   the  highest  permissable
computer  -  to - modem speed (check your manual). The  V.32xx  or  V.42bis
modem will take care of modem to modem speed.


                                   Don Hinds - Zoom Tech
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