3G Service Only On 900 Mhz?

[cityslicker]

I have an old iPhone 3G purchased in U.S., unlocked and working with AIS here. When AIS rolled out 3G service, I could not (and still cannot) get 3G service; stuck with EDGE (2G). I believe this is because the phone is only tri-band for 3G (850, 1900, 2100; see tech specs at http://support.apple.com/kb/sp495), but AIS is using 900 MHz. Can anyone confirm? And does DTAC or True use one of those other frequencies, such that if I switched providers, I could get 3G service? (If so, I assume it's easy to port the phone number?)

Thanks for any help.

[khonlanna]

If I remember correctly,

AIS: 900MHz, 1800MHz

DTAC: 850MHz, 1800MHz

TRUE: 850MHz, 1800MHz

TOT: 1900MHz, 2100MHz

and all these 4 providers provide 3G

[cityslicker]

Thanks! I'll pick up a SIM for one of the others and give it a try.

[khonlanna]

If you have an old 1-2-call! SIM, you might need to have it exchanged at any AIS office. Old SIMs don't support 3G.