Zoiper Communicator SoftphoneScreenshot 

 

ZOIPER Communicator is a very intuitive SIP softphone, with presence, chat, video and fax. Very stable, small footprint, skinnable, and with encryption support. It comes with a built in peer 2 peer voip service, so that you can speak chat and videotalk with other users even if your pbx or voip provider does not support those features.

Screenshot of Zoiper Communicator Softphone