The problem is that there are very few companies making baseband chips, and to say that they do not care, at all, about hobbyist applications, would be the understatement of the year.
As it turns out, even your smartphone is probably right now talking AT to its baseband processor. If you get one of these mobile surf sticks, it's probably a virtual COM port and the software on your computer is giving AT commands. As horrible as that sounds, it is the standard they use.
I always had this secret hope that the AT interface was a translation layer on top of their sensible protocol (kind of like, say, x86 on top of microcode), and that one day someone would have the bright idea to just expose the underlying one.
As it turns out, even your smartphone is probably right now talking AT to its baseband processor. If you get one of these mobile surf sticks, it's probably a virtual COM port and the software on your computer is giving AT commands. As horrible as that sounds, it is the standard they use.