X-Lite is a proprietary freeware VoIP soft phone that uses the Session Initiation Protocol (SIP). X-Lite is developed by CounterPath Corporation, a Vancouver based software company. Version 4.0 was released in September 2010. X-Lite complements other non-free products offered by the company, like Bria, Bria iPad, eyeBeam, mobile gateways and SIP based developer tools.
X-Lite is available for Windows and Mac and can be used to make audio/video calls and to send Instant Messages to a softphone, mobile or landline telephone number. X-Lite has some outstanding features. A comprehensive user guide is provided. I use X-Lite with a SIP account from my Internet provider Visual-Online in Luxembourg.