Data roaming is expensive especially for Canadian and Americans. It's handy to have data on your phone while you navigate in and out of the streets (they dont have English street signs most of the time), calls Grab(Thai uber), unlocks shared bikes, etc.
Multiple phone companies offer tourist sim card, but the one with best value is the Happy Cards offered by DTAC.
- there are 3 main types of plans, ranges from 7-15 days
- 299baht for unlimited mid speed internet for 8 days
- 599baht for unlimted high speed internet for 15 days
- 199baht for unlimited slow speed internet for 7 days
- You get call credits, amount varies per plan
- Plan details: https://www.dtac.co.th/en/prepaid/products/tourist-sim.html
- You can buy them at any local 7-11 convenience stores
- If you are flying into Bangkok you can order online and pick up at airport upon landing