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Open Source SIP Stack and Media Links



Recommended Open Source Portability Framework

If you're looking for the base portability/framework library for building your application, then I can recommend the following fine libraries:

APR Apache Portable Runtime, a fine C library/framework for building portable and high performance applications.
ACE Adaptive Communication Environment, a fine C++ library/framework featuring many design patterns for building portable and high performance applications.

PJLIB contains many functionalities as found in APR and ACE. It is written in C and it takes portability to extreme level.



Recommended Open Source Media Components

If you're looking for some components/libraries for your multimedia applications, then I can recommend the following fine software libraries:

PortAudio a fine portable cross-platform Audio API written in C for abstracting sound devices on Windows, Windows Mobile/WinCE, Unix, Linux, MacOS, etc.
resample a fine library for performing high level sample rate conversion.
Speex a fine audio codec! (what else can I say)
PJMEDIA a media framework suitable for embedeed/DSP or desktop development alike.



Open Source SIP (Session Initiation Protocol) Stacks

Please find below links to opensource SIP stacks are actively maintained at the time of writing:
NIST SIP Java SIP stack as reference implementation of JAIN API, so it's has good API and documentation. It also has reference implementation for servers and user agent.

GUI user agent and SIP stack with focus on security, and is portable across Win32, Windows Mobile, Linux, and Linux iPaq. Supports audio and video. [LGPL].

mjsip SIP stack written in Java, with layered API approach. Applications include servers and user agent with audio and video capabilities. [GPL]

SIP stack with media, written in C++ and depends on PWLIB. The website has reference implementation for SBC and also an ActiveX component for building SIP user agents.

Footprint is quite large (megs?), but it has media stack implementation (with video?) too. [MPL]

osip2 and exosip2

One of the earliest open source SIP stack, so it enjoys good number of adopters.

Footprint is quite small (several hundreds KBs), and supported ports include Windows, Linux/*nix, VxWorks, MacOS X, and many embedded targets. Media stack is available via commercial license only. [GPL or commercial].


PhoneAPI from OpenWengo project, written in C. It says to provide easy to use high level API for developing SIP audio and video user agents.

Ports include Linux, Windows, and MacOS X. Media stack included. (GPL)


The SIP (and media) stack features in this website.

PJSIP SIP stack is written in C and is mainly targetted for small footprint, feature rich user agents, although it has attracted some server side developments too.

Footprint is very small (<200KB), performance is very good (thousands of calls per second), and it is very very portable (Windows, Windows Mobile (WinCE, PDA, SmartPhone), Linux, *nix, MacOS X, *BSD (FreeBSD), RTEMS, Symbian OS, etc.), which makes it good candidate for embedded developments. Complete media framework is available with PJMEDIA. [GPL or other]


C++ stack from SIPFoundry non-profit SIP community project. The community is backed by many commercial companies and it hosts health number of active developers. (Vocal)

Sofia SIP

A SIP library written in C for building SIP clients. Supports many SIP call, presence, instant messaging features, as well as TCP, IPv6, TLS, and STUN support.

Footprint is quite small (several hundreds KBs), and there is user agent reference implementation which uses gstreamer for the media. (LGPL)



Other SIP and Media Directory

Open Source VOIP Software A wealth collection of open source VoIP links.
Henning's SIP Page

Very good place to look for SIP.

Klaus Darilion's VOIP bookmark

Wealth number of SIP and media links, worth checking.




If you like to update any information in this page or want to add an entry to this page, please send email to me (bennylp at



Open Source Links

- Open Source Base Framework/Portability Libraries 

- Open Source Media Components

- Open Source SIP (Session Initiation Protocol) Stacks

- Other SIP and Media Directory

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