I know there are a lot of these companies around the track which offer cheap rate international calls, but I found this particular one to be exceptional.

It's called Vopium and their "Call Unlimited" plan gives you up to 2000 minutes worth of calls a month for only 10.29 (plus the cost of a local call to your mobile/landline operator): http://vopium.com/unlimited (you can also pay in other currencies).

It doesn't matter whether you use a landline or a mobile. There's no static and audio is always crystal clear.