3G is now wide spread in Thailand however you have to check your phone for the compatibility.
The big 3 operators now offer 3G on various frequency, none offer on standard UMTS2100.
AIS 3G use 900MHz
DTAC 3G use 850MHz
Truemove-H use 850Mhz
Double check your phone compatibility before opt out for sim card.
For local call or ISD call there are no much difference between them, you can check the old topic in this forum for more info.
Moreover Truemove-H is not the same network as Truemove which is only offer 2G service (though own by same company). Many news customer encourage to apply for Truemove-H which can roam into Truemove for 2G service where 3G network is not available.
By far IMO Truemove-H offer little better of 3G service than the other, while AIS offer reliable and good voice service. DTAC is losing its reputation in the country with poor service and network down frequently.
Any question on Thai's sim card? Put it here or PM me.
