Products

Linphone

is an open source instant messaging and voice/video over IP (VoIP) phone that makes it possible to communicate freely with people over the internet via voice, video and text messaging.

Since it follows open standards from the telecommunications industry (SIP, RTP), Linphone is interoperable with most PBXs and SIP servers, including our own Flexisip server, and can be used with any SIP VoIP operator.

Discover complementary products in our complete solution for instant messaging and IP-to-IP calls, such as Linphone applications, Liblinphone cross-platform VoIP SDK and Flexisip server.

Many new features are still under development on a medium- or long-term basis. Please feel free to contact us if you want to know more about our development roadmap, or if you are interested in financing the development of a particular feature.

About us

Linphone for smartphones and tablets

Linphone is one of the most famous open source softphones in the world. It is fully SIP-based, for all calling, presence and IM features.

Use Linphone for free, and enjoy its intuitive interface and advanced features with our free SIP service or with an existing SIP account.

Easy-to-use graphical interface :

account creation assistant
smart contact list, with address book synchronisation for smartphones
call history
“Invite your friends” option
remote provisioning from a QR Code or a URL

Advanced calling features :

HD video calls with video preview (H.264, H.265 and VP8 codecs supported)
audio/video conference calls and scheduled meetings
call transfer and multi-call management (pause and resume)
call recording and replay (audio only)

Increased audio and video quality :

state-of-the-art adaptive jitter buffer algorithm
innovative adaptive bitrate control
HD voice (Opus support) and echo cancellation
call quality indicator and display of advanced call statistics

Enhanced Instant Messaging experience :

one-to-one and multi-participant conversations
intuitive message delivery status (IMDN)
file sharing (photo, video, document, voice/video message)
reply to / forward / copy options
multi-device support
advanced IM notifications, with “reply to” and “mark as read” options

Secure communications :

secure user authentication
end-to-end encryption of audio/video calls, messages and shared files
post quantum encryption
ephemeral messaging

Technical corner

Available for:

Android

iOS

About us

Linphone for desktop platforms

Linphone for desktop platforms is perfectly suited for both standard users with no specific knowledge of VoIP/SIP and for advanced audio/video calling use cases in a professional environment.
It is fully SIP-based, for all calling, presence and IM features.

Use Linphone Desktop for free, and enjoy its modern look and feel and its many advanced features with our free SIP service or with an existing SIP account.

Complete, intuitive User Interface :

simplified user experience with swift access to major features
intelligent search bar for ease of communicating
contact list with presence status
unified call and chat history
quick access to your recent events
multi-account and multi-device support

Enhanced Instant Messaging Experience :

instant messaging with file sharing and groups
access to chat views during calls
intuitive message delivery status (IMDN)

Advanced calling features :

HD video calls in full screen mode (H.264, H.265 and VP8 codecs supported)
optimised audio/video quality, thanks to our new jitter buffer and bitrate adaptation algorithms
HD voice (Opus support) and echo cancellation
audio/video conference calls with up to eight participants, with three display modes (active speaker, mosaic, audio only)
multiple call management (pause and resume)
call transfer, auto-answer, DTMF support
call quality indicator and display of advanced call statistics
secure communications with SIP/TLS, SRTP and ZRTP and post quantum encryption

Technical corner

Available for:

GNU / Linux

macOS

Windows Desktop

About us

Linphone web integration

Linphone Desktop is now able to interact with web browsers and can be integrated with your Web Services.

Since we are experiencing increasing demand for advanced solutions for professionals, we have made Linphone for Desktop capable of receiving information from a web browser to start a call, open the app, invite participants to a conference call etc.

Demo page

Available for:

Safari

Firefox

Edge

Chrome

About us

Liblinphone SDK

Liblinphone is a high-level open source library that integrates all the SIP-based voice/video calling, conferencing and instant messaging features into a single easy-to-use API.

This is the VoIP SDK engine on which Linphone applications are based!

Liblinphone combines our media processing and streaming toolkit (Mediastreamer2) with our user-agent library for SIP signaling (belle-sip).

Signaling features :

user authentication via digest (SHA256 or md5) and TLS client certificates
multiple call management: hold, resume, transfer and more
multiple SIP proxy support: registrar, proxies, outbound proxies
presence using list subscription to presence server
DTMF (telephone tones)
interoperability with IMS networks
suitable for building a VoLTE-compatible client

Media features :

HD audio calls with support for Opus codec
HD video calls with support for H.264, H.265 and VP8 codecs
state-of-the-art adaptive jitter buffer algorithm
innovative adaptive bitrate control
ICE support for optimised NAT traversal
end-to-end media encryption using SRTP, SRTP-DTLS and ZRTP protocols
post quantum encryption using Crystals-Kyber algorithm
audio and video call recording

Instant Messaging features :

one-to-one and group instant messaging
ephemeral messaging
voice/video messaging
delivery and “is typing” notifications
end-to-end encryption for one-to-one and group conversations
file sharing, with configurable settings to automatically / manually download attachments

Consult our technical corner to see the list of supported standards, download pre-compiled binaries or the SDK source code, and find more information about available tutorials and documentation.

Technical corner

About us

Flexisip Server

Flexisip is a complete and scalable SIP server suite that includes several modules: a proxy, a presence server, a conference server, a back-to-back user agent, and Flexisip account manager for the creation and administration of SIP accounts.

Flexisip is an easy-to-install SIP server solution, offering all the features required to deploy your own SIP service tuned for mobile or desktop applications, « out of the box ».

The free sip.linphone.org SIP service has run on Flexisip since 2011, and enables Linphone users to create their own SIP addresses to connect with each other.

Proxy :

NAT-aware with built-in media relay module and ICE/STUN support
interconnected with Apple’s and Google’s push notification systems
high availability and cluster mode for large deployments
high-level event logging for activity monitoring
digest and TLS client certificate authentication

Presence :

Flexisip manages SIP SUBSCRIBE and PUBLISH from client applications, in order to :

identify users of the service within the address book
provide users with real-time presence status

Conference (for group chat and group calls):

entirely SIP-based solution
efficient management of groups and participants
multi-device support
notification of group events (users joining or leaving, new admins etc.)

B2BUA:

media encryption transcoding
media codec transcoding
SIP bridge, for interconnection with PSTN gateways

Flexisip account manager:

SIP account creation and management, by end-users or admins
remote provisioning of Linphone-based apps (including app’s settings, user account, contact list…)
web admin platform

Flexisip can be integrated into your SIP infrastructure for various purposes, for example IN THE CLOUD in order to run your own VoIP service, EMBEDDED in small hardware systems or in its PUSH GATEWAY mode of operation.

Technical corner

Other components

Post quantum encryption engine

The Linphone application is most likely the very first open source software in the world to provide post quantum encryption to secure voice and video communications. For that purpose, the Linphone team developed a modified version of ZRTP, the well-known encryption protocol. This module is an extension to the bctoolbox library providing Post Quantum Cryptography using the Crystals-KYBER algorithm.

Technical corner

Tunnel: VoIP anti-blocking solution

Our tunnelling solution has been developed for VoIP operators who wish to bypass VoIP blocking in some countries or illegitimate firewall restrictions on 3G networks.

All SIP and RTP traffic is tunnelled through a single secure https connection to a detunneliser server.

Technical corner

Linphone Instant Messaging Encryption

Linphone Instant Messaging Encryption library (LIME) provides end-to-end encryption for instant messaging, allowing users to exchange messages privately and asynchronously. It supports multiple devices per user and multiple users per device.

LIME offers two major security benefits to Instant Messaging users:

End-to-end encryption, which means that only you and your contact (and not even the server) can decrypt the content that you shared
Perfect forward secrecy, which ensures that encrypted messages cannot by decrypted by a third party, if a key is compromised in the future

Technical corner

Mediastreamer2

Mediastreamer2 is a powerful lightweight streaming engine for voice/video telephony applications.

This open source library is responsible for receiving and sending all multimedia streams in Linphone, including voice/video capture, encoding and decoding, and rendering.

Technical corner

Bcg729

Bcg729 is an open source implementation of both encoder and decoder of the ITU G729 Annex A/B speech codec.

The library is fully portable and can be executed on many platforms including both ARM and x86 processors. libbcg729 supports concurrent channels encoding/decoding for multi call application such as conferencing.

Technical corner

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