Quick Start Manual

AT Command Set Reference C-1
Appendix C
AT Command Set Reference
This appendix provides information for using AT commands for the Model XM128 ISDN Digital
Modem.
Operation Mode of the DTE Interface
The operation mode for the DTE interface is Simplex mode. This mode is used for conventional
AT command operation.
Simplex Mode
In simplex mode, the Model XM128 modem is used just like an ordinary modem. The DTE
interface is either in the command state or in the data state. Only one data connection session is
possible at any time.
To perform various functions of the Model XM128 modem, a number of different AT commands
can be used. The simplex mode is designed for AT command users. The guides and descriptions
throughout the rest of this manual, if not otherwise specified, are applicable to this mode. The
power-on default of the DTE interface is in simplex mode as well.