Best answer by Mohammed
Welcome to our iD Community!
Are you currently in Thailand or you mean that your friend is in Thailand and his texts are not coming through to you in the UK?
This would be something your friend would need to pick up with his network provider.
We would only be able to investigate issues where you're unable to send text messages.
If you're having issues receiving a text message from anyone at all we can look into this further.
EDIT: I've moved your post to a new topic for you in the Coverage, international & roaming section of our community.