Zoiper

Zoiper 2.0 IAX & SIP softphone (previously known as Idefisk) now supports T.38 Fax over IP. Zoiper is a VoIP soft client, meant to work with Asterisk and SIP-capable IP-based communications systems and infrastructure. Zoiper is available for Windows, Mac OS X and Linux. Zoiper 2.0 Free (previously known as Idefisk) is a light application that provides basic and advanced VoIP functionalities at the cost of a click. Download for free. Take a quick look at the advanced features of Zoiper Free: