There's many pre-paid SIM cards you can choose from. The best place to buy these are from the 7-11 stores, which seem to be everywhere in built up shopping / tourist areas. You can get top-up cards of 100, 200, and 300 baht (about 8 USD). If you text message international numbers you will run out of credit quickly - but it's still probably cheaper than global roaming with your provider from home. almost 7 years ago
I suggest you buy them directly at the airport. 7-11 always sells top-up cards, but not all 7-11 stores sell pre-paid SIM cards. Just the prepaid SIM card costs 50 baht, and then you need to top it up.
1-2-call is the best choice if you plan to travel around Thailand, overall they have the best network connectivity. If you stay in BKK, every company will be fine. almost 7 years agoAnswered by Somphon via Travellr.com