The alternative is called Skype.
Skype official website – free download and free calls and internet calls
I have a lot of friends all around the world, and it's very easy to reach them like that. It is an application for the PC which enables you to chat with other people who also have it installed for free, like it is also possible through MSN, ventrilo, teamspeak, ...
However, what differs skype from all those other applications, is that you can sign up for a premium account and use Skype not only to call someone else who's also using it on his/her PC, but you can call any number on the world. It works a bit like a prepaid card, you sign up for the premium account, buy a prepaid card for your account and then you're free to call ( or also send SMSes ). It is WAY cheaper than anything else. I checked it, and a call from wherever on the world to a thai mobile number is about 0,1 € / minute.
I can vouch for them, as I'm using the services myself, just like a lot of other people I know do. They are very serious, the network's always up, and the one and only downside is that you will have to sit on ur PC / Laptop to call (you need a headset for that). However, I'm sure it could reduce your costs by at least 90 %.
Hope this helps.