Another option............ we usually take our notebook computer with us and we have gizmo (gmail version of chat)
As long as we have internet in the hotel, we can call other gizmo users and talk live to them for free and we can call other people by calling their landline or mobile from our computer - there's a small charge for this.
Last week, I made 3 hours of calls from Hong Kong to Australia and it cost me AUD 5 about 1/4 the price of discount IDD or phone cards here.