Globalstar Product Management – Technical Support

Customize Globalstar Modem Negotiation using AT+MS

The AT command set for Globalstar phones and modems includes the commands AT+MS and AT+CFG.  These commands offer the ability to customize the behavior of the Globalstar Gateway modems so that they are more compatible with specific applications such as encryption devices, utility meter reading software, and others.  Until now, there has been no published documentation of these commands.

This document applies to the GSP-1700, GSP-1720, GSP-1600, GSP-1620, and GSP-2900.


The Globalstar Gateway IWF does not support any useful user configurable +CFG input.


+MS commands can be used to define the data interface standard (to the PSTN) as follows

  • v.21 300bps, full duplex
  • v.27ter 4800/2400 bps half duplex
  • v.32 9600 bps full duplex
  • v.32 bis 14000 bps full duplex
  • v.42 error correction
  • v.42bis compression/ error correction.

Qualcomm tested several options which successfully configured the IWF to work with a modem. These options were limited by the type of modem and network.

  • e.g. to set IWF as v.32 with max and min baud rate fixed at 9600 bps use following command where V32 is the standard, 0 or 1 equals automode on or disabled, 9600 is fixed min rate, 9600 is the fixed max rate.
    • at+MS=V32,0,9600,9600   results in a V32 connection at 9600 bps
    • at+MS=V32,0,4800,4800   results in a V32 connection at 4800 bps
  • For V.xx bis the command is entered as follows V1xx
    • at+MS=V132,0,9600,14400,9600,14400                modem connection autobauded back down to 9600

Although V.22 and V.22bis are not stated as being supported by the Gateway IWF, Qualcomm tested the following successfully, as the VOCAL modem (VOCAL Technologies, Inc.) which is used by the IWF, actually supports this standard.   Note …. This has not been fully tested but appears to work.

  • at+MS=V22,1              modem connected as V22 at 1200 bps
  • at+MS=V122,1    modem connected at V22bis at 2400 bps.

All the above scenarios were able to transfer data at the specified standard.

IMPORTANT NOTE: The +MS command does not provide a response back to the terminal other than OK.  However, it is possible to concatenate the +MS command into a multi-command AT string.  For example:


will echo back the new +MS string.  This is sometimes useful in automated scripts.


Additional keywords:  asynch analog

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