I've been researching M2M for new products we have been developing.
The main players are
Telit (HE910 sereis), Italy
Sierra Wireless (HL6528/HL8548), Canadian
Quectel (UC20), Chinese
Gemalto EHS6, French
U-Blox (Lisa and Sara), Swiss
I'm not sure if there is even a USA company that plays in this space.
All the modules are of similar sie but have incompatible footprints.
Essentially, these modules will embed a Broadcom SOC and a custom OS. Broadcom was charging the module makers too much, so they have started moving to Intel and others. These product cost mega bucks to develop, and even after you buy a module with all the R&D done, you still need to spend a another $60k in certification if you want to get it on the AT&T network (per product).
There is going to be a lot of growth in this area as people develop IoT gateways. (as we are doing)