SIP and RTP Stack

Note: I only searched for C/C++ stacks and applications. There also exist a lot of stacks and applications for other programming languages, especially for java. If you are looking for Java stacks/applications, please ask Google. If you have any comments or interesting links, or do you want to report broken links, please contact me

RTP Stacks (mainly open source C/C++ stacks)

jrtplib: C++; License: Free; Homepage: http://lumumba.luc.ac.be/jori/jrtplib/jrtplib.html
Common Multimedia Library: from UCL London, includes RTP stack; C; License: Free; Homepage: http://www-mice.cs.ucl.ac.uk/multimedia/software/common/
ortp: C; License: LGPL; Homepage: http://www.linphone.org/ortp/; without RTCP, from linphone
GNU ccRTP: C++; License: GPL (with linking exception); Homepage: http://www.gnu.org/software/ccrtp/
LIVE.COM Streaming Media: C++; License: LGPL; Homepage: http://live.com/liveMedia/
Morgan RTP DirectShow Filters: C++; License: ?; Homepage: http://www.morgan-multimedia.com/RTP/; based on liveMedia library
RTP from vovida.org: C++; License: Free; Homepage: http://www.vovida.org/protocols/downloads/rtp/
RTPlib: RTP library from Lucent Technologies/Cloumbia University; C; License: Non-exklusive source code license; Homepage: http://www-out.bell-labs.com/project/RTPlib/
librtp: C; License: GPL; Homepage: http://gphone.sourceforge.net/template.php3?page=librtp; from Gnome-o-phone

SIP Stacks

dissipate: C++; License: GPL; Homepage: http://www.div8.net/dissipate/; The original dissipate by Billy Biggs.
dissipate2: C++; License: GPL; Homepage: http://www.wirlab.net/kphone/; A enhanced dissipate, is part of the kphone distribution.
GNU osip; C; License: LGPL; Homepage: http://www.gnu.org/software/osip/; Also known as libosip. Note: The interface of osip has been changed and from now on it will be called osip2!
GNU eXosip; C; License: GPL; Homepage: http://savannah.nongnu.org/projects/exosip/; The extensible osip: "...It aims to implement a simple high layer API to control the SIP for sessions establishements and common extensions. Once completed, this eXtended library should provide an API for call management, messaging and presence features....
SIP from vovida.org: C++; License: Vovida Software License; Homepage: http://www.vovida.org/protocols/downloads/sip/

RTP Applications

RAT - Robust Audio Tool; Supports a large number of codecs, ... License: Free; Homepage: http://www-mice.cs.ucl.ac.uk/multimedia/software/rat/
JMF - Java Media Framework: Can receive and send RTP streams; Homepage: http://java.sun.com/products/java-media/jmf/
MP3/RTP Plugin for Winamp: Homepage: http://www.live.com/multikit/winamp-plugin.html
Vomit - Voice over Missconfigured Internet Telephones: Plays back captured voice conversation; Homepage: http://vomit.xtdnet.nl
RTP Tools: Several RTP utilities from the Columbia University; Homepage: http://www.cs.columbia.edu/IRT/software/rtptools/
UDP Packet Reflector/Forwarder: A tiny tool which forwards or reflects UDP packets. You can also add delay and packet loss. Very useful if you want to test RTP applications. Homepage: http://www.cs.ucl.ac.uk/staff/s.bhatti/teaching/z02/reflector.html. As I was not able to compile this tool I searched and found a binary somewhere in the web. You can download it local

SIP Phone (User Agent, Softphone, Proxy)

Ubiquity User Agent: Java based SIP Client for Windows, very useful, you have to register (free) to get an license; Homepage: http://www.ubiquity.net/useragent.php
Linphone: A SIP Softphone for Linux (GNOME), needs libosip ans oRTP; Homepage: http://www.linphone.org/
KPhone: A SIP Softphone for Linux (KDE); Homepage: http://www.wirlab.net/kphone/index.html
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
AVAZ SIP Phone: Cool looking SIP Phone for Windows, crashes very often at my PC, but works well on my friends PC; Homepage:http://www.avaz.com/products/software/sip/index.html
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/
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.
SJPhone: SIP and H.323 Softphone for Windows, Linux and PocketPC from: http://www.sjlabs.com/. The configuration for SIP is a little bit tweaky. And there must not be another SIP client running on port 5060 or the SJPhone won't work.
instant xpressa: The software version of the xpressa SIP phone from pingtel: http://www.pingtel.com/appdev.jsp; A really impressive SIP phone with a lot of features. Can be extended with Java programs, but no free version available.
xphone: A SIP client for Windows and Windows CE, http://xphone.xten.net/. The beta version is free.
SIPPS: SIP softphone with answering machine and a lot of features, but, IMHO, a not very intuitive user interface, which should be better in the next version (try it yourself).http://www.sippstar.com/. A Demo for testing is available.

SIP Test Utility

sipsak: SIP Swiss Army Knife, very useful test utility (Linux); Homepage: http://sipsak.berlios.de/
SIPNess: Ortena Networks SIP Messenger, very useful test utility for windows; Homepage: http://www.ortena.com/download.htm

SIP Applications (Proxy, Location Server)

Sip Express Router (ser): Highspeed GNU SIP proxy with a lot of features and a lot of ongoing development. Homepage: http://www.iptel.org/ser/. A really cool SIP proxy - I like it! You can also take a look at the development homepage.
Asterisk: Linux Software PBX with Gateway, SIP Proxy, Gateway (SIP, H.323, PSTN, ...); Homepage: http://www.asteriskpbx.com/

Commercial SIP Stacks

Juphoon SIP; C; High Performance SIP stack, Homepage: http://www.juphoon.com/en/products/protocols_voip/sip.htm
SIP Phone (User Agent, Softphone, Proxy)
JPhone: Juphoon Phone Framework, Juphoon provides voip phone, video phone, 3G IMS PoC, IMS UE soultion. http://www.juphoon.com/en/solutions/solutions.htm