Could anyone tell me if this phone can be operated in Thailand.

these are the frequency specs

UPP8 v.6, Dual-band variants: EGSM 900/1800 (EU) and GSM 850/1900 (US) – EDGE only

Where did you buy the phone?

If in Europe you'll be ok as that version will do 900 Mhz (AIS/One2Call) and 1800 Mhz (Dtac, Happy and True Move).

If bought in America it'll only do 850 Mhz and 1900 Mhz, both frequencies are AFAIK not used in Thailand for GSM voice service. True uses the 850 Mhz band for their limited 3G trials, but I doubt they do voice on that band.

Dtac is also licensed on the 850 Mhz band, but is not using it, they used to offer the old analogue mobile phone service in that band.

Thanks!