[dannzeman]

There's two networks: CDMA and GSM. A phone with a CDMA radio should work on any CDMA network. The trick is getting a provider to let you use a phone on their network that they didn't sell you. For instance, you sign up for a contract with Sprint, buy a phone (CDMA) and then want to switch to Verizon or Alltel. Since Verizon and Alltel are CDMA you should be able to use the phone you bought from Sprint on either of their networks, but since you didn't buy your phone from Verizon or Alltel they probably won't activate for you.