It's hard to explain. Nextel and Sprint are one company... but still on two different networks. Sprint users have the almight ev-do network... while Nextel users as myself still have the out-of-date iDen network. Sprint says that it's going to convert the Nextel network to Cdma... but it's not happening fast enough for me. The last i heard, it wasn't going to be upgraded until the end of '07 (OUCH).
FYI: The reason nextel kept the out-of-date iDen network was because it was the best in providing there highly in-demand "Push to Talk" feature which is almost the only selling point they have. But now since it's being offered over Ev-Do (Cingular)... They have problems