Tourist pre-paid SIM with True since 2015. Top up with 50 Baht occasionally from my Thai bank account when out of the country, then:
Extend SIM validity for 30/90 days
- 30days at 3Baht, press *934*30#
- 90days at 9Baht, press *934*90#
The short codes work in EU even with data roaming off, as long as international access is enabled
HTH