Controlling the modem

Hi Guys,
I am a newbie to Apple software development - have done most of my work in the PC world. I'd like to write a little program to control the modem, having it pick up calls, detect tones and transmit tones. Can any seasoned developers point me to the modem API or let me know how I can go about doing these things? I'm very comfortable with signal processing so the tone detection and transmission isn't my major worry - I just have no idea on where to look for API stuff (tried apple's site but seems to be mostly web related stuff)

Thanks much.