How to communicate with USB 3G modem?
Ok folks, thank you for all your thoughts and your input. I have done some more research, and finally i realized, that in order to do what i wanted i did not have to bother with serial ports and AT-commands at all. All that was needed was to do a few Windows RAS calls.
If I had just been a bit more specific in my question about what I wanted to do with my AT-commands, you would surely have told me about RAS long time ago!
I found a nice .Net DLL (DotRas) that wraps native Windows RAS for use from managed code, and it seems to do just what I need (dial a 3G modem connection from code, with any type of 3G modem I attach).
Thank you again for your time.
You can use GetCommState(), after obtaining the handle via CreateFile() with target COM port: