Originally posted by michaelsanford
I presume you mean recording a telephone conversation with the modem?
I've not heard about that specifically, but you can head down to your local electronics store and get a suction-cup microphone that you attach to pretty much anything (telephone handset, door, etc) and just use any old recording app (like Amadeus II or Sound Recorder).
PS At least here in Canada it's illegal to record someone on the phone without their consent...