communicating with a modem

I need to write a program similar to windows hyperterminal.

Problem is i need to automise the process so that my program can send AT commands to a modem and recieve responses back. Without human interferance.

I need to either emulate the hyperterminal or communicate directly with the device.

Any ideas how I can do this ??

I'm doing something similar to this right now, but it's for Posix-compatible operating systems. I shouldn't think it's any more difficult in Windows.

If I were you, I'd google for it and see what kind of code you can find; that's where I got my basic info for Posix serial programming.