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Chapter 4. Troubleshooting 21
To force different communication
speeds
Type these AT commands
and press Enter
Negotiate speed and protocol
(default setting)
AT &F
To force protocol
AT \N3
Dual mode (V.90 or V.92)—56000
bps
AT+MS=V92,1
V92 only (disable V.90)—56000 bps
AT+MS=V92,0
V.90 only (disable V.92)—56000 bps
AT+MS=V90,0
Disable both 56K and auto rate on
V.34—33600 bps
AT+MS=V34,1
V.34—33600 bps
AT+MS=V34,0
V.32bis—14400 bps
AT+MS=V32B,0
V.32—9600 bps
AT+MS=V32,0
2400 bps
AT+MS=V22B,0
1200 bps
AT+MS=V22,0
Notes:
Some software allows these commands to be added to
the list of dial prefixes or the initialization string.
•
When the protocol is forced, the modem will not attempt to
connect at other protocols if it cannot connect at the forced
protocol. It will try to connect at the fastest speed available
within the forced protocol.
•
There are other configurations that can be forced as well. If
you need to select a particular configuration, use the AT
command strings shown below. You can always return to the
modem’s default configuration by typing
AT &F
and pressing
the
Enter
key.
Remember that if you do this, the modem will not have received
the commands in your software’s initialization string as it normally
would. Using the
ATZ
command overcomes this problem if you
have saved all of your setup parameters in nonvolatile memory.
(To save setup parameters in nonvolatile memory in
AT
com-
mand mode: Type
AT
, followed by the parameter settings you
desire, followed by
&W
, and press
Enter
. For example, if you
type
AT &C1 &D2 &W
and press
Enter
, the
&C1
and
&D2
pa-
rameter settings are stored.)