VoIP - SIP and RTP stacks, softphones, user agents, STUN

SIP Phones

baresip: A multi-platform SIP client with SIP and RTP stack, audio and video codecs under BSD license. Website: http://www.creytiv.com/baresip.html.
QjSimple: A cross-plattform GPL SIP client with support for presence, instant messaging, TLS and SRTP. Aimed for developers with a dedicated DEBUG window and configuration support.http://www.ipcom.at/index.php?id=560
x-lite, x-pro: A SIP client for Windows; Mac OS and Windows CE, http://www.xten.com/index.php?menu=download. A really nice SIP UA with a lot of features. The light version is free and really rocks, the pro version not. Supports multiple proxies.
MiniSIP: An open source SIP user agent for Linux which runs on PDAs. It is based on several libraries, including libmsip, a C++ SIP stack. Homepage: http://www.minisip.org/index.html.
OpenWengo: A Windows softphone based on Qt and eXosip. Open Source.http://www.openwengo.com/.
KPhone: A GPL SIP Softphone for Linux (KDE). Note: Development moved from wirlab to sourceforge. Homepage: http://sourceforge.net/projects/kphone . The old kphone (which was originally maintained by wirlab) can still be download at http://www.wirlab.net/kphone/kphone-4.2.tar.gz
Microsoft portrait: Windows SIP client that supports Audio, Video and IM. Uses RTC API 1.2 and therefore has poor compatibility with other SIP clients.http://research.microsoft.com/~jiangli/portrait/.
Ubiquity User Agent: Java based SIP Client for Windows, very useful, you have to register (free) to get an license; Homepage: http://www.sipcenter.com/sip.nsf/html/User+Agent+Downloads
EZ-Phone (Evaluation Version): SIP Phone for Windows; Homepage: http://www.hssworld.com/voip/download.htm
MySIP: SIP User Agent from Siemens; Homepage: http://www.mysip.ch/
SJPhone: SIP and H.323 Softphone for Windows, Linux and PocketPC from: http://www.sjlabs.com/. There must not be another SIP client running on port 5060 or the SJPhone won't work.
Linphone: A SIP Softphone for Linux (GNOME), needs libosip ans oRTP; Homepage: http://www.linphone.org/
Vovida: Complete SIP Suite for Linux (Uaser Agent, Proxy, ...), very, very big software contruct; Homepage: Vovida.org
Siphon: Linux SIP Softphone; Homepage: http://siphon.sourceforge.net/index.html
ActXPhone: An ActiveX-Control SIP Softphone based on the Microsoft Real Time Communications (RTC) API.http://www.pernau.at/kd/voip/ActXPhone/.
sipXphone: Part of pingtel's open source releases for VoIP. License: LGPL; Homepage: sipfoundry.org. This softphone also requires lots of other libraries from the sipX... software at sipfoundry.org.
SIPPS: SIP softphone with answering machine and a lot of features. They have also integrated support for nikotel.com for SIP-PSTN termination.http://www.sippstar.com/. A Demo for testing is available. The configuration is a bit weird (what's the difference between a proxy and a redirect server?).
MSN Messenger: Microsofts Messenger, Version 4.6 allows also connections to other SIP servers than microsofts one. Nice design, works very well. Can be used with the SIP service of iptel.org. Homepage: http://messenger.microsoft.com; local download of Version 4.6 for Windows NT (2000).
MSN Messenger: Microsofts Messenger, Version 4.7 allows also connections to other SIP servers than microsofts one. Nice design, works very well. Can be used with the SIP service of iptel.org. Homepage: http://messenger.microsoft.com; local download of Version 4.7 for Windows XP.

Shtoom: An open source, cross plattform SIP client written in Python. License: LGPL; Homepage: http://divmod.org/projects/shtoom.
Cornfed SIP-UA: A SIP user agent for Linux. License: Free for non-commercial use (binary distribution); Homepage: http://www.cornfed.com/products/.
PhoneGaim: The multiplatform, multiprotocol IM client GAIM was extended with VoIP (linphone based) by linspire/sipphone. It's open source! At the moment it's in a beta status and supports only sipphone.com as SIP proxy, but as the source code is also available, you can change this by yourself ;-). Homepage: http://www.phonegaim.com/.
SFLphone: A multiplatform, open source SIP user agent. It is based on several libraries: cc++, ccRTP, osip2+eXosip. Open Source. Homepage: http://www.sflphone.org.
ENUM softphone: An ENUM enabled SIP client based on the RTC API. Open Source. Homepage: http://www.enum.at/index.php?id=292.
Phoner: A Windows softphone which supports dialing via an internal ISDN adapter (CAPI), TAPI or SIP. Freeware. Homepage: http://www.phoner.de.
Twinkle: A Open Source Linux softphone based on Qt and ccRTP. Homepage:http://www.twinklephone.com/.
BOL SIP Phone: A Windows softphone based on the MS RTC API and WinStun. Homepage:http://www.bol2000.com/download/sipphone/.
sipXezPhone: A Windows/Linux softphone based on the sipXtapi. License: LGPL, Homepage:http://www.sipfoundry.org/sipXezPhone/.
sillyAnt: The first freely available SIP softphone for Symbian Series 60, unfortunately this SIP phone is locked to TiVi. Homepage:http://www.sillyant.com/.
pjsua: Windows SIP phone based on the PJ... stacks. License: LGPL; Homepage:http://www.pjsip.org/pjsua.htm
PartiSIPation: A SIP client with replaceable GUI. License: GPL; Homepage:http://developer.berlios.de/projects/partisipation/.
Ekiga: A Linux SIP and H.323 softphone, based on GnomeMeeting; Homepage:http://www.ekiga.org/.
zap!: A cross platform SIP client based on the Mozilla framework; Homepage:http://www.croczilla.com/zap.
sua: A Linux SIP client. Looks like this project is rather old and dead; Homepage:http://sua.sourceforge.net/.
eyeP Media: This is not a softphone, but a softphone SDK. License: commercial; Homepage:http://www.eyepmedia.com/.
Zfone: Zfone is not really a SIP phone, but an extension to any SIP phone. It implements the ZRTP protocol for secure media streams. This is done by intercepting the media stream from the SIP phone and adding the ZRTP extension. Homepage:http://www.philzimmermann.com/EN/zfone/index.html.
Tapioca: Tapioca is a VoIP and IM client. It supports XMPP (allows communciation with Google Talk) and SIP (uses Nokia's sofia SIP stack). Homepage:http://tapioca-voip.sourceforge.net/.
Kapanga: Kapanga is free for personal use (after registration). It runs on Windows and supports video. Homepage:http://www.kapanga.net/.
ATL Softphone: A SIP softphone for Windows based on the OpenSipStack. License: MPL1.0. Homepage:http://www.opensourcesip.org/softphone.php.
YateClient: An open source multiplatform softphone which supports SIP, H.323 and IAX. Homepage:http://voip.null.ro/pmwiki/index.php?n=Main.YateClient.
Zoiper: A SIP/IAX2 softphone. It's using reciprocate as sip stack and has an in house developped iax2 stack - both function at the same time and you could do a conference between them. Supports Windows. Mac and linux versions are planned. The "Free" version is free to use. Homepage:http://www.zoiper.com/.
Jitsi: A Java based SIP client and multi-protocol IM application with video support. License: LGPL. Homepage:https://jitsi.org/.
UTC IMS Client: A IMS compatible SIP Client for Linux, written in C, based on eXosip. License: GPL. Homepage:http://uctimsclient.berlios.de/.
Lynxphone: A commercial multiplattform SIP client; based on resiprocate STIP stack; A free version is available at http://www.bitlynx.com/lynxphone.php. Offers nearly the same settings as eyebeam (as based on the same stack). The german translations are really funny! The user interface is crap.
VO2IP: VoVoIP (means voice over voice over IP) is a proof of concept implementation which hides a G.729 encoded audio stream into a G.711 encoded fake audio stream using G.711's least significant bit. It is GPL licensed, based on pjmedia (see SIP stacks) and runs under Windows. Homepage: http://voipcc.gtisc.gatech.edu/.
wxCommunicator: wxCommunicator is a cross platform GPL SIP softphone. It is based on sipXtapi and wxWidgets 2.8.x GUI library. Homepage: http://wxcommunicator.sourceforge.net/.
SIPek Phone: a Windows softphone based on pjsip SIP stack. Includes a pjsip .NET wrapper. License: ? (but as it is based on pjsip i guess it is GPL too). Homepage: http://sipekphone.googlepages.com/.
SIPek2 Phone: based on SIPek phone, but a new C# GUI. Homepage: http://sipekphone2.googlepages.com/.
PuppySip: A GUI wrapper for pjsua (console based SIP client included with pjsip SIP stack) http://tmxxine.com/wik/wikka.php?wakka=PuppySip.
MizuPhone: A Windows softphone with TLS, Presence and XCAP support. A free version is available. http://www.mizutech.hu/.
PortSIP: A Windows softphone and VoIP SDK. A free version of the softphone is available from http://www.portsip.com/.
FaramPhone: A Windows softphone with video support. A trial version with reduced features is available from http://www.faramtech.com/.
YASS: A multi-plattform softphone written in Python (uses Python Qt bindings for the GUI), based on pjsip SIP stack. License: GPL http://dev.sipdoc.net/projects/yass/wiki.
Homer Conferencing: A multi-plattform videophone which supports local calls without server or SIP based calls. Suports multiple sessions and desktop broadcasting. License: GPL2 http://www.homer-conferencing.com.