Here are the APN settings for DTAC Trinet :
Name: dtac internet
APN: www.dtac.co.th
User name: not set
Password: not set
MMC: 520
MNC: 05
APN type: Default
To set for iPhone:
Settings > General > Network > Cellular Data Network
To set for Android:
Settings > Wireless and Network (More) > Mobile Networks > Access Point Names > New APN
or
Settings > More > Mobile networks > Access Point Names
DTAC can send you these settings OTA (Over The Air) if you visit: http://dtac.co.th/ota