Have you ever got a spam from your mobile phone company that does not come from your own mobile company? The big once, AIS, DTAC and True move have invested 30 million to stop the SMS spam but I never get spam other than from True.
Sometimes I get over 10 SMS from true in one day but I never spread my phone numbers around like asking for credit card or something.
The guys who stand around the city promoting credit card will get about 100 THB for your information and then they sell that info in big lists. Then everything from property to fitness companies will start sending you SMS.
I do not see the big problem here just make a law that forbids spam and you can put a big X on your contract that you do not want to have any spam from your cell phone company and then file a police report every time someone spams you.
I will try one off these days to call True and ask them to stop sending me SMS but I am not sure how long it will take me but I will be sure to print the conversation here, should be amusing.