Both Sprint and Verizon Wireless use CDMA phones ... no SIM Card is used ... the provider
of service must activate the phone. Sprint, I think, uses Java on their phones so most games
are ok. Verizon Wireless uses BREW which is next to impossible for most games designed
for Java to run on. You can, however, change the Firmware on your phone, to say, one from Alltel
which does have Java and pretty much returns all the phone makers features to the phone that
carriers like Verizon, like to cripple, so you need to buy things like ringtones from them.
However, if you do that, you need to find all the correct settings to make it work on your network.
And in most cases, that type of mod, while legal, would void any warranty on the phone.
There are a few cell phone hack / mod sites out there that can get you through it. And some phone
makes can not be changed by the average users. Motorola phones, are easily hacked.
As to the question of EVDO it is used for location identification and also for better roaming coverage.
Downside is lower battery life as the phone is always checking to see where it can get coverage from.