AT Commands to a usb fax modem to retrieve the caller id

This project involves a simple usb modem router that supports AT Commands, and an android tablet. What I need to be done is to be able to send AT commands to usb modem that will be connected in the android tablet so that I will be able to get the “Caller ID” when a call is being made to the telephone that is connected to the fax modem. The caller id should be able to be passed inside an android application. Thank you.