Svenn has said so many things here that don't make sense. But may be he is right this time.
To me it's not quite clear what he is doing or up to:
Sim2Fly is a special Thai roaming SIM by AIS with special packages intended for Thai roamers abroad. These SIM cards work roaming all over the world. That's their purpose.
http://www.ais.co.th/roaming/sim2fly/en/
Regular (one-two-call) AIS SIM cards for Thailand normally don't roam abroad or at a very high price.
These two product lines are intended for different purposes: domestic and abroad (seen from Thaland).
They come in different AIS SIM cards and can't be changed to one another.
To verify his observations, he is very unclear in what he is exactly doing. Asking him for specifics, he evades direct responses.
So I wonder which way he is suggesting exactly in his post?
- Did he take a regular (1-2-call) AIS SIM, added this unlimited throttled package intended for Thailand and it works in Germany too at the Thai domestic rate (which is surprising)?
- or did he take a SIM2Fly AIS roaming SIM and was able to add this same unlimited throttled pack destined for Thailand (which is surprising) and thereby roams at the Thai domestic rate in Germany?
The approach to both ways is very different as you need a different SIM card to do this.
Generally, I'm sceptical and we can give him a chance and try to verify this. But for that he needs to specify exactly what he is doing.