Modem Scripting newbie question

[Phenex37]

Hi,

I've just been asked to write a modem script for an external modem connected to a Windows 7 box.

I've an understanding of the AT commands, but I have no idea how to write/compile and test any script I write. I can write a text file with the AT commands in but have no idea how to 'send' these instructions to a connected modem.

Any pointers?

thanks

Mark