3Com 56K manual You can use the AT%Fn command to control the data format

9-6CHAPTER 9: ACCESSING AND CONFIGURING THE BUSINESS MODEM REMOTELY

You can use the AT%Fn command to control the data format.

To change the data format to	Command
No Parity (8 data bits)	AT%F0
Mark parity (7 data bits)	AT%F1
Odd Parity (7 data bits)	AT%F2
Even parity (7 data bits)	AT%F3

You can use the AT%Cn command to control whether and when to apply changes to the configuration

For your modem to	Command
Defer configuration changes to when the call	AT%C0 (Default)
ends.
Restore the original configuration.	AT%C1
Use this command to cancel any changes made
during remote access and restore the original
configuration.
Force configuration changes.	AT%C2
Use this command to make configuration changes
take effect immediately. We do not recommend
forcing changes unless it is absolutely necessary
because an unreliable connection, or even a loss
of connection, may result.

Example: Sending AT%C1 will cancel any changes made to the modem during a remote access session and restore it to the original configuration.

Even though, by default (%C0), the changes you make do not take effect until the next connection, the new configuration is reflected immediately in inquiry responses (ATIn).

Commands that have been written to NVRAM (using &W) and forced configuration changes (%C2) will not be restored to their previous settings when you send the host AT%C1.

After you make changes to the host’s configuration, the remote- access prompt changes from Remote->to Remote+>.