What's the cheapest and the best Quality way to make an internationall call in Thailand?

I have stayed in Thailand for a year and I have to make calls to oversea. What do u suggest ?

Admin : You can use call through system, you can call landlines and cell phones. I have heard its pretty good! Let 's try VoiceClear 001.

With VoiceClear001, the quality of the call is just as good as 001 and users in the office do not notice any change

VoiceClear001 is not like any other VoIP services I have seen, they commit us on the digital quality and they deliver exactly what they promise………..
Since I tried VoiceClear001 our international bill reduced by 40%.

Using VoiceClear001 is very easy as if dialing 001 or 009. Registration takes less than an hour and we can start calling immediately