AT Commands
Page 187
AT+MS Select Modulation
The +MS command selects the modulation, optionally enables or disables automode, and
optionally specifies the lowest and highest connection rates using one to six subparameters. The
command format is:
+MS= <mod>
[,[<automode>][,[<min_rate>][,[<max_rate>][,[<x_law>][,[<rb_signaling>]]]]]<CR>
Subparameters not entered (enter a comma only or <CR> to skip the last subparameter) remain
at their current values.
The maximum speed in bps of the modulation is bound by the DTE speed in bps. If the DTE
speed exceeds the maximum capable by the selected modulation, then the DTE speed has no
effect in limiting the resultant modulation speed on connection. If the DTE speed is less than the
maximum capable modulation, then, (resulting connection modulation speed) < (DTE speed)
For example:
1. DTE speed: 19200 bps
Modem configuration: +MS=11, 1, 300, 19200
Maximum obtainable modulation speed: 19200 bps
2. DTE speeds 38400 bps
Modem configuration: +MS=11, 1 300, 33600
Maximum obtainable modulation speed: 33600 bps
This feature allows the modulation over the telephone line to be more reliable and give better
throughput, since the maximum throughput obtainable is governed by the DTE speed.

<mod>

A decimal number which specifies the preferred modulation (automode enabled) or the
modulation (automode disabled) to use in originating or answering a connection. The options are:
<mod> Modulation Possible Rates (bps)
0 V.21 300
1 V.22 1200
2 V.22bis 2400 or 1200
3 V.23 1200
9 V.32 9600 or 4800
10 V.32bis 14400, 12000, 9600, 7200, or 4800
11 V.34 33600, 31200, 28800, 26400, 24000,
21600, 19200, 16800, 14400, 12000,
9600, 7200, 4800, or 2400
12 ■V.90 56000, 54667, 53333, 52000, 50667,
49333, 48000, 46667, 44000, 42667,