Yes it really workes
You will get an SMS You can enjoy now unlimited Data with 1 mbit for example.
I'm roaming on the german Telekomnetwork.
Here you can look at the packages
https://thaiprepaidcard.com/ais-512-...-baht-30-days/
The packags are vaild for 30 days.
Just top it up here and it will work
https://www.recharge.com/en/thailand/ais-top-up