Sip calling?

[inkognito]

My boyfriend and I found this websites, it offers low rates (if you are in USA, Britain or some similar country) to call other countries. These websites are called sip websites and basically you are kind of calling through Internet but by phone. I don't really know how it works, but I know that you pay about 2 cents for 1 minute of the talk time.
You can google it, its very popular.
I didn't see the similar thread, so sorry if I have repetition

[Aaron]

I use that. I got myself a number that was local to my SO over a year ago and it's just really nice to see the caller ID come up correctly for them like they were calling from down the street. :3
Plus it's nice that they can call me because my SO can't make regular International calls, for some reason. So this gets around that.

[Jade_Crystal]

First time I hear about this. Any recommendations or tips? I wonder if there are any country or credit card limits.