Although mobile casinos are incredibly popular in Thailand, they are limited by the law. The gaming Act of B.E. 2478 (1935) outlaws almost all types of gaming in Thailand. The national lottery and horse racing in Bangkok are two notable exceptions to the general scope of this law.
Since internet and mobile Thailand gambling are not specifically included in the gaming Act, they fall into a legal limbo. Given that online gaming is not specifically mentioned, players may face possible danger if they end up playing.
The issue gets much more ambiguous when talking about mobile casinos based in other countries. Thai gamers are able to use these sites since they are based in countries other than Thailand. It's not technically illegal to gamble at offshore mobile casinos, but you shouldn't do it either. As a result, Thai players need to be wary while interacting with mobile casinos based in other countries.