Re: coverage on GSM; AT&T and T-Mobile has great coverage within the Triangle. There are a few deadspots, but we do have access to the latest and greatest wireless in the US (we're usually one of the first rollout markets, thanks IBM, Cisco, etc). But... if you're looking at a GSM based MVNO you have to consider a few variables and what you really value.
- Coverage area
- Handsets
- Price/month
- Carrier flexibility
- International flexibility
For coverage, Verizon is impossible to beat. I'm on AT&T and I get a signal where there's civilization. AFAIK, T-Mobile can be spotty, but it's pretty fast. When going up to VIR, I don't have coverage from when I turn onto NC-86 until I get to VIR.
Handsets: You can get any one you want on Verizon, as long as it's the one that is only available on Verizon. Verizon has the worst selection here, and you're also tied to the IMEI/CDMA functionality. You can buy second hand phones off of eBay, but you are going to need to call up Verizon and do the song and dance to get it to work. GSM phones are plug and play once you have the handset, and you have options like the Google Nexus phones.
The price/month on Verizon is at minimum $70/month for service (not counting discounts), whereas you can get on Straight Talk for $45, or go further down the rabbit hole and get $30/month ones if you start digging and like a personal challenge of only using 100 minutes/month. There are CDMA independent carriers, but I think they all give you Samsung/LG burner phones that have no data attached to it.
Carrier flexibility is largely independent on the handset radios, but there are a number of phones that you can use on both AT&T and T-Mobile with no issue (including their MVNO piggybacks). I would assume that the CDMA phones are the same way, but then you're only able to use either Verizon or Sprint.
International flexibility: CDMA = US, Canada, Brazil, South Korea, and a handful of other countries; GSM = Everywhere else. I don't know how international CDMA works exactly, but I would figure that it would be easier to just buy a burner phone to use overseas. With a GSM phone, you can buy a SIM at the airport with some prepaid minutes + data on it, and plug it into your phone and be good to go. Try not to lose your US SIM card, though.
