It's never going to work in Thailand because 48 don't support roaming there.
If it's not working in France then it could be the usual iPhone roaming problem due to the stupid way that Apple do things.
You may have to try this and it can take many attempts before it works.
Toggling airplane mode on and then off and then quickly trying it may help to get the phone to "catch" the local network briefly allowing the configuration changes to be made.
Hope this helps.