If you make a lot of phone calls get a Thai network SIM phone card. Put it in your phone if it is not locked to a network. A phone shop will set it up for you – well worth any extra payment as mine and a friends phone card would not work properly for 24 hours when I set it up myself. You can get top up cards from convenience stores like 7/11. Best coverage one2Call other networks DTAC & True (Orange), you can get mobile internet on your laptop. Internet Cafes sell SIM cards & are everywhere. Mobile Phones are expensive in Thailand but calls are cheap.