Try this cross-network instant messaging tool

Phone calls from mobiles and landlines are cheaper than they ever have been, and the service is generally reliable to but the fact is, it still can't compete with instant messaging, especially if you have friends and family abroad. Another plus point is that communicating in this way enables you to talk to people on a one-to-one basis as well as in groups. However, one downside is that because there are so many different messaging clients available it's pretty unlikely that all your friends and family will be using the same one.

Miranda 0.8.0 is a free instant messenger client that enables you to communicate across almost anyone, irrespective IM network. All status icons are included for other networks and your contacts are consolidated onto a single list. Unfortunately the application doesn't support all advanced features that ship with some IM tools, but it's a small price to pay for the convenience of using a single application.

Miranda 0.8.0 link.