Linphone

Linphone is an open source softphone for VoIP calls, video calls and instant messaging, published by Belledonne Communications. It addresses the need for a modular real-time communication stack: organizations can deploy a ready-to-use application, integrate calling features into their own products, or build a complete secure communication solution. The project has been developed in France since 2001.

The product line includes the Linphone softphone for desktop and smartphones, the Liblinphone cross-platform SDK, the Flexisip modular SIP server suite (account and configuration management, call routing, chat, conference and presence), Mediastreamer2 as the media streaming engine, the Bcg729 G.729 codec implementation, and encryption modules covering ZRTP end-to-end call encryption, instant messaging and conference encryption, plus post-quantum protection. The softphone is compatible with third-party VoIP platforms and is available in white-label form under open source or proprietary licensing. Services include rebranding, server installation and configuration, annual maintenance support and custom development.

Linphone targets individual users, developers and network administrators, as well as enterprises and public organizations looking to modernize VoIP infrastructure. The application and Linphone service are available for free use, with community resources such as a FAQ and support space; source code and pre-built versions are downloadable, and licensing is offered under open source or proprietary models.