Sorry, I did not review the specs on the SE handset very carefully. It will not work on the 1-2-Call (AIS) network as it does not support GSM900, so you will be limited to DTAC (Happy) and TrueMove on GSM1800. I doubt there is GSM1800 coverage throughout the country. It would be OK in Bangkok on DTAC. I would strongly recommend a GSM900-capable handset.