Linphone is an open source and multi-platform web phone application that lets users to call their friends from anywhere in the world without paying for more that the actual cost of their Internet connection.
Similar to Skype, the application provides almost the same functionality and features, except that it is written in GTK+ and integrates well with the GNOME, Xfce, LXDE, Openbox and Fluxbox desktop environments.
Features at a glance
The application allows users to make voice calls, initiate video conferences, as well as to text their friends using the IM (instant messaging) protocol. For the Internet phone system, the application makes use of the open standard and well known SIP protocol.
To call someone, users must provide a SIP (Session Initiation Protocol) URL that looks like an email address. You’ll have to known the SIP URL before initiating a phone call, but you can also use a standard IP address.
In more technical terms, the application comes with a SIP UA (User Agent) that’s compliant with RFC 3261, supports the IPv6 protocol, supports SIP/UDP, SIP/TCP and SIP/TLS protocols, as well as digest authentication.
Supports multiple calls and SIP proxies
In addition, the application supports multiple calls at the same time and multiple SIP proxies (outbound proxies, registrar, etc.). It also includes delivery notification support for the instant messaging component.
Standard call management features are provided, including hold on with music, call transfer or resume. DTMF (telephone tones) support is also included, based on the RFC 2833 or SIP INFO specifications.
Supported operating systems
It is an ultra portable application, that has been successfully tested with Linux, Windows, MacOS X, Android, iOS, BlackBerry and WebOS operating systems. The 64-bit, 32-bit and ARM architectures are supported.
Summing up, Linphone proved to be a very good alternative to Microsoft’s Skype Internet phone application. It is actively developed, runs on multiple platforms and provides a neat collection of codec plugins.