I've got a iPhone 3GS using True 3G, purchased here from True. I'm moving back to the USA in a couple months and hoping to use my Thai iPhone there.

I've recently read reports that all four main carriers in the USA (Sprint, AT&T, T-Mobile, Verizon) keep a database of MEID #s and will refuse to allow an "unofficial" (i.e. not purchased from them) phone on their network, apart from some networks which allow foreign carrier roaming, but with some limitations of service. Another issue I'm aware of is the GSM frequencies the US carriers use are reportedly not the same as those used here in Thailand.

I've used my iPhone in Australia without any trouble at all, but I know the USA is not Australia. I should mention that I'm not talking about roaming, but as a local carrier subscriber - I'll be moving there permanantly.

Does anyone here have any such experience?

MEIDs are only for CDMA phones, not GSM phones. You are correct that Verizon and Sprint won't allow MEID of devices not sold by them on their networks. But since you don't have a CDMA device the point is moot. You have a GSM device and it uses an IMEI, not an MEID, and you will have no problems using the device anywhere in the world with a few exceptions. You can use the phone on T-Mobile or AT&T by simply inserting a sim. They allow any device as long as it does not "harm" their network. If you want 3G speeds then you need to go with AT&T as the frequencies they use are supported by the iPhone (AT&T and True Thailand use the same 850Mhz band for 3G service). In some areas AT&T uses 1900Mhz which is also supported by your iPhone. T-Mobile uses a non-standard AWS frequency that is not supported by the iPhone.

Edited January 3, 201214 yr by jackbox

Do you know where you will be in the U.S.?

Do you require 3G, or is 2G sufficient?

Your only options are T-Mobile, but 2G only for your phone, or AT&T.

If AT&T then you may have to activate/register the SIM with a non-Apple phone, after which time you could switch it to your iPhone.

You can review the T-Mo and AT&T coverage maps and plans. T-Mo is easier to activate, and has some great month-to-month plans which are ideal for your time but 2G on data only. I use T-Mo as the 2G is fine for me. AT&T does have Data Feature Packages, $25 for 500 MB, which may include 3G.

Remember you pay for incoming and outgoing calls and SMSes.

Thanks for the feedback! I guess that's good news. I'll be moving to LA. I'm definitely hoping for 3G speeds, however since I'll be living in the USA for only 5 or 6 months (then moving back to my home in Australia) I may have to consider a month to month plan and maybe have to settle for EDGE speeds.

Wow, they pay for incoming as well as outgoing calls and SMSs there?? Crazy! It's easy to complain about how backwards Thailand is, but I get unlimited 3G data, and never use all of my huge monthly allotment of hours and SMS, for roughly $25. What an awesome deal!