I have a Sony Ericsson T237 brought over from the US. It's been unlocked and accepts an AIS sim, but can't find a network. It's a GSM 800/1900 MHz phone...do any of the Thai providers use one of these frequencies? I've read Thailand works on 900MHz, 1800 MHz and 1900MHz bands, but apparantly AIS does not use 1900Mhz. Any ideas?

Won't work, the two main providers are on 900 MHz (AIS) and 1800 MHz (Dtac).

I think 800 MHz is not in use anymore, I think it was used only for the older analogue systems before gsm came around.

Hence most quad band phones here are 800, 900, 1800 and 1900 MHz...with the 800/1900 only to be able to use it in the states. Europe uses mainly 900/1800 as well.

DTAC and TrueMove are 1800, AIS 900. I believe.

Seems you are SOL, if you are here temporarily you could buy a cheapie second hand phone.

Hello

First of all, the mentioned phone is dual band GSM 850/1,900 and not 800/1,900. It won't work with AIS, which utilises GSM 900 and GSM 1,800 via own network and subsidiary "GSM 1800" (also displayed as "DPC 1800" or "Hello"), that's the network's name!

The mentioned Sony-Ericsson phone can be used in Thailand only on the "Suthep Net" network, which is available as "Thai Mobile". Pre-paid SIM cards are available, it's called "Sawasdee", but the network coverage is VERY sporadic, that network never really got off the ground due to non-existent marketing. It still covers, to my knowledge, only greater Bangkok and the rest of the country by roaming on AIS - which said phone can't work with.

Best advise: If in Bangkok, take a trip to Mahboonkrong ("MBK Center") and look around on the fourth floor. More mobile phones there that you could ever buy Cheap "grey imports" new phones as well as tons of second-hand ones. If you get a quad-band (850, 900, 1,800 and 1,900) you can use it here and in the U.S.A., most tri-band (very common nowadays, working on 900/1,800/1,900) will also work on most U.S. networks. Phones sold in Thailand are generally unlocked.

Networks in Thailand:

T.O.T. Analog: NMT 470. Still covering many parts of Thailand, almost no longer used but operational. No pre-paid, no new phones.

TAC "New 800" Analog: NMT 800, covers the whole country. Still used mainly up country. Pre-paid available! But no new phones, and no new registrations of old phones that were out of service (i've got some and tried it!).

C.A.T. CDMA (digital): IS-95 (partly EV-DO??), CDMA 800. Covers whole country. No information about pre-paid.

Hutchison "Hutch" CDMA (digital): 2000-1x, CDMA 800. Covers central Thailand, outside roaming on C.A.T. CDMA. Pre-paid available: Hutch "Say" (it's CDMA but uses SIM cards!).

T.A.C. "D-TAC" (former "World Phone")(digital): GSM 1,800. Covers whole country, EDGE coverage whole network too. Pre-paid available: "Happy D-Prompt".

A.I.S. "GSM Advance" (former "GSM 2 Watts")(digital): GSM 900, covers whole country. EDGE in some areas. Pre-paid available: "One-2-Call".

A.I.S. "GSM 1800" (former "Hello", a.k.a. "DPC 1800")(digital): GSM 1,800, data service only by switching to AIS 900. Coverage sporadic, mostly major cities but countrywide on AIS 900. No pre-paid!

TRUE "TRUE Move" (former "Orange")(digital): GSM 1,800, coverage countrywide (with "white spots"). EDGE available in certain areas. Pre-paid available.

Suthep Net "Thai Mobile" (digital): GSM 1,900, data service unknown. Coverage very sporadically, mostly Bangkok. Nationwide roaming on AIS 900. Pre-paid available: "Sawasdee". Need tri-band phone to use this network!

Kind regards.....

Thanh