I think that AT&T has the next best coverage. Their 3G footprint is nowhere near Verizon, but for basic phone calls, text messages and lower-speed data, AT&T works practically everywhere Verizon does. Also, if you get a quad-band GSM phone from AT&T it will work in most foreign countries (but you'll pay through the nose if you don't unlock your phone and get a local SIM card).

Sprint, except for the old NexTel service, uses the same technology as Verizon, (CDMA), but the phones are not interchangeable (due to carrier lock-downs), and they do not seem to have cross-roaming agreements. Their coverage is nowhere near Verizon or AT&T. But I think that in 911 (Emergency Call) mode they will connect you via a Verizon cell.

Boost, Cricket, MetroTel and many of the more economical pre-pay carriers are reselling Sprint service, so the same caveats apply as for Sprint.

Note that NexTel, although a Sprint product, is a completely different technology (iDen) and coverage is limited to metro areas and major highways (and surrounding areas). Outside of this they are a paperweight.

T-Mobile also uses GSM, and you can interchange phones if you get them unlocked. But, in spite of their coverage map, T-Mobile's reliability is reported to be the worst of all (except NexTel) and although the phones use GSM there is no roaming agreement with AT&T.

I currently use AT&T and my kids and I are generally satisfied.

I've used AT&T, Verizon and Sprint and my observations are:

1. AT&T has the best nationwide coverage for voice calls.
2. Verizon has the best nationwide coverage for 3G data.
3. GSM, used by AT&T, is the global standard for cell phones.
4. CDMA, used by Verizon and Sprint, is rarely available outside North America and a few Asian countries.
5. GSM phones can be unlocked so you can just replace the SIM card to change carriers.
6. CDMA phones can not be interchanged between CDMA carriers.
7. As far as I've discovered, all the inexpensive Prepay Cellular Providers actually resell Sprint.
8. Sprint has the worst coverage and reliability (as of 2004) and the poorest selection of phones
9. Sprint has the worst customer service, but none of them are much better.

Coverage Maps:

• AT&T Wireless
• Verizon Wireless
• Sprint PCS
• NexTel Connect (click the Sprint PCS link then click the NexTel tab).
• T-Mobile (Note: Reports indicate real-world coverage is not as good as indicated on map.)