Wikipedia
X-Lite is a proprietary freeware VoIP soft phone that uses the Session Initiation Protocol.
In September 2010, the Vancouver based CounterPath Corporation released X-Lite 4.0, which incorporates many of the features from X-Lite 3.0 but has a redesigned user interface based on CounterPath's Bria softphone.
Past releases of X-Lite include: X-Lite 2.0 for Linux, which uses the old X-Pro code base, and X-Lite 3.0 for Windows and Mac OS X which uses the eyeBeam base. X-Lite 2.0 was audio only, while X-Lite 3.0 had audio, video, and instant messaging as well as being presence-capable.
In 2005, X-Lite was Internet Telephony magazine's Product of the Year. X-Lite complements other non-free products offered by the company but misses functionality needed to use it within a company such as transferring calls.