Not receiving SMS from international numbers

ljv wrote:

Depends on the country. I have not been able to receive an SMS from Greece since December (and they cannot receive them from me either) but that is not true of all countries. Maybe T-Mobile will one day decide to have its engineers actually work on it. 

Mentioning Greece specifically does help narrow things down a lot.  I don't know anyone in Greece to test whether or not texting works.  Correct number formatting when calling and texting is very important in both directions.  Have you tried reaching out to Customer Care to make sure there isn't a block on international calls and texts on your line?