Vbuzzer Messenger is a messenger client and VoIP app in one package. It is compatible with the networks of MSN, Yahoo, ICQ and AIM, in addition to having its own network.
As well as basic functions such as chat, checking your mail and send and receiving files, it lets you make phone calls worldwide and send and receive faxes at rates comparable to Skype. In addition, there's an easy to use RS reader and the overall feel and design is quite nice. The PC-to-Phone rates are low and the audio quality is usually very good. I also liked the fact that you can setup call forwarding to any landline or mobile phone, free voicemail to e-mail service and record your own personal voicemail greetings. The PC-to-phone service is known as BuzzOut while the phone-to-PC service is named BuzzMe and enables subscribers to receive unlimited calls on Vbuzzer. You get a free area 416 BuzzMe number that can be reached from any phone and they usually have introductory offers with a range of free calls on offer.
I wouldn't change to this from Skype but if they could lower the rates a bit, I'd definitely consider it.