You just sign up, choose your countries, yes Thailand is one of them, and phone for up to 10 mins free!
Its advertisment driven so that according to them is how they can offer the service.
In their own words... PokeTalk offers consumers the ability to make completely free phone calls, from both landlines and mobiles. In addition, there is absolutely no need for headsets, microphones, PC speakers, or any other accessories or special adapters.
When ready to make a call, place the number you want to dial as well as your own, and then PokeTalk takes over and does the rest of the work for you!
After pressing call, your phone will ring instantly and then automatically you will be connected to the person you are dialing. All domestic and international calls are totally free because costs against them are paid by advertising revenue generated on the PokeTalk web site.
I haven't had time to try it yet, but it looks worth a punt...
