When a AT command is sent to a modem it should automatically set the baud rate correctly.

A number of cell phones will not work above 19200bps. 19200 is the recommended baud rate for cell phones.

The Seimens M20 does NOT auto detect the baud rate.

Before the modems did compression of the data the modem would change the baud rate that it talks to the PC to that of the connection. This was done so that flow control would never be needed.

All modern modems have the ability to not change the baud rate that it talks to the PC/receiver. A number, especially land line modems, have the ability to have the baud rate follow. This is not a good thing as the receiver will not change baud rates to follow. The &B1 command (AT &B1) turns off changing baud rates for a number of modems.Note that having a baud rate > 9600 normally turns off this feature.

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