I used italk card to call Thailand. I loaded it with my cell phone number. The transaction to buy the credit was done very fast, but the services I get is the worst. I tried to call my friend in Thailand but there is no sound at all after the operator mentioned how much the duration available for the number I called. My friend on the other side heard the ring but the call remained silence when he answered it.
To make sure the phone line is working, I did call without using my italk credit and the line got connected. I tried to make a call to TM customer service line but my call was transfered a few times and was HUNG UP. I did it again for 2 more times and the same thing HAPPENNED. In view of the worst services they had, I would not recommend any investing company to help such a loser country I lived in. I would advise some companies to set up as a competitor to explore this monopolized sector that had not been challenged for a long time.
Finally, tried not to buy italk card, it is not worth it. Use internet or other form of international calls.