I recognize Nokia -- they're the folks that make the phones that actually work, except when the batteries fall off while you're talking. They seem willing to make phones for any system since I have seen them for Sprint, Verizon, Cingular and ATT.
I'm pretty sure that the main economic concern for the folks deciding which system to go with is the power cost of running the towers. This would be affected by the broadcast frequency and the compression technology that allows many channels in the alloted band.
Geex ... you didn't quite nail it at all.
What you cited actually plays very little in making the decision as to which technology to employ.
THERE ARE currently only two bands in use in the USA - and EACH air-interface/RF standard is going to make the most of any compression schemes ...
The choice of mode (again, the "Air-interface standard") is coming down to 'modes' that area compatible with Europe's (GSM format) systems.