RCM 6700 & GPRS module

I have a RCM6700 and GSM / GPRS modem M10. Communication is OK. Internet connection via PPP protocol OK. But I can not switch the data / command mode. I need to be connected to the Internet and monitor incoming calls.
Switch to command mode can only close and open serial port, but then i lost connection.
There is another way switch modes?

You mean that ,are you sending AT commands to the GSM/GPRS modem through the one of the serial port on RCM6700?

If you want to monitor only incoming calls, you can get that information through the AT commands, so at that time At command mode is fine, no need to change it(modem’s state ) to the data mode.