Leaving the US for our annual winter in Thailand. The Thai wife wants to get a high end phone here purchased online as unlocked to take back there. She has looked at Lumia925, but here she loves her Iphone 4S. Me, I prefer to get calls on my cell and compute on a computer, so I have never learned that stuff. I understand there was a USA problem about CDMA and GSM or such, so I worried about buying something here and taking it there.

1) Is this issue now gone? are smartphones all now just smart phones or is there still a protocol problem.

2) Any knowledgeable recommendations appreciated on models and purchase locations

Not an expert of any sort with regard to this....but what I can tell you is that the phone I use here in Thailand (samsung) works fine in the USA....Thailand is on the GSM band as is T-mobile....so all I do is switch out sims.....

Now your question is coming from the US to Thailand .....need to find out if your phone is a Dual band GSM/CDMA or at least GSM.....if so you may be able to bring you phone from the US and just buy a Sim card in Thailand for it....But not sure if the US phone has to be "unlocked" in order to work in Thailand.

I think prices are fairly comparable from US to Thailand .....so easiest thing might be to come to Thailand to buy a phone and then bring it back to US

ATT, T-Mobile, and possibly Virgin Wirelss are GSM Networks so their phones should all work on Thai networks provided the phone has been unlocked and it is a quad-band phone. A call to customer service should get your phone unlocked to work on other networks provided you qualify. Depending on the company the qualification is likely to be being a current customer, having had the phone being used for last 6 months on your account and phone is not under contract.

If you don't qualify there are plenty of unlocking services online, just provide the IMEI number of the phone and they give you a code to unlock. I just did this today as a matter of fact because the phone I am taking to thailand next week has only been on my account for 3 months. Cost $3.20 for my particular phone.

Thanks for the care and bother of answering. Its exactly the quadband type issue i am worried about. Why would a manuf. bother making a quad band for the locked up USA market? We are looking at buying a phone just to take back and the ones we look at were from what I think is a compatible carrier system like T-mobile or ATT. In the US we live in the Catskill Mountains and service generally is spotty and only the verizon system is worth owning, which is clearly not a compatible system. So, we look to buy on online (saving $100 or 200) over a high end phone in Thailand. Used Iphone4 for instance and they are advertised as factory unlocked. So, would seem to work, but lots of concern that I will miss something.

You need to say "mobile" as 90% of the world won't know what your talking about with the strange term of "cell phone".

Thanks for the care and bother of answering. Its exactly the quadband type issue i am worried about. Why would a manuf. bother making a quad band for the locked up USA market? We are looking at buying a phone just to take back and the ones we look at were from what I think is a compatible carrier system like T-mobile or ATT. In the US we live in the Catskill Mountains and service generally is spotty and only the verizon system is worth owning, which is clearly not a compatible system. So, we look to buy on online (saving $100 or 200) over a high end phone in Thailand. Used Iphone4 for instance and they are advertised as factory unlocked. So, would seem to work, but lots of concern that I will miss something.

You can see the specs of the phone you are interested in at gsmarena.com .

For info on the thai networks there is plenty of information in the thai visa internet and communications forum.