Is it possible to build a basic modem out of the ATmega168? I am thinking about building a Caller ID decoder and that would require being able to read a 1200 bps data stream consisting of 1200 Hz (Logical 1) and 2200 Hz (Logical 0) signals.

Or would it make more sense to hunt down a "modem on a chip" to do this for me and control it with the microcontroller? I did a search at digikey, but wasn't sure exactly what I was looking for.

Thanks.