Windows app interfacing with EVDO/GSM devices thru AT calls

jackfl

I currently support a Windows .Net application which interfaces with Verizon 1xRTT/EVDO/RevA devices via a nice 3rd party SDK, and am looking to add support for some additional devices. I will be writing my own interface to these devices, perhaps an SDK, and it looks as if AT commands are the common denominator for most WWAN devices. My questions: is there any good documentation on the web concerning using AT commands to interface to WWAN devices? Has anyone already tried to do this? I'm also looking at GSM devices, and hope that the major differences would be supported via AT command extensions (hopefully publicly available). Thanks.