Unicom cards only accept short messages abroad.

According to the information you provided, if you can use Unicom's number to receive domestic short messages and make phone calls in Thailand, it should be that the number has opened international roaming service. You can find out whether you have opened an international roaming service by querying your roaming level. You can log in to the online business hall/sabmm;

4G primary and secondary cards:/02 UPY;