Linphone

Linphone is a comprehensive, open-source real-time communications suite developed in France since 2001. It combines a cross-platform softphone, modular server components, and a VoIP/IM/video ecosystem designed for secure, interoperable communications across desktop and mobile. With features like end-to-end encryption, post-quantum security, and flexible deployment options (on-premise, private cloud, or SaaS), Linphone is suitable for individuals and organizations alike.

• Softphone for VoIP, video, and instant messaging
• SDK Liblinphone and open APIs for easy integration
• Flexisip modular SIP server
• Mediastreamer2 media engine
• End-to-end encryption: SRTP, ZRTP, and post-quantum (Cristals-Kyber)
• WebRTC compatibility and SIP interoperability
• Cross-platform support (iOS, Android, macOS, Windows, Linux)
• White-labeling and branding options; open-source or proprietary licenses
• Deployment options: On-premise, Private Cloud, or SaaS (coming 2025)
• Active community and documentation

• Fully open-source with transparent code and community-driven development
• French origin and ongoing development by Belledonne Communications since 2001
• Interoperable with standard SIP-based VoIP ecosystems and widely portable across infrastructures
• Modular architecture with Linphone, Liblinphone, and Flexisip for flexible deployments
• Strong security posture including end-to-end encryption and post-quantum capabilities
• Flexible licensing (GPLv3 open-source or proprietary options) and customization/branding potential

• Free to download under open-source GPLv3
• Proprietary license option for source-code access and commercial deployments
• Availability of custom development, support contracts, and managed services (quotes on request)