VoIP User : A UK based free SIP based network with a community funded PSTN gateway
Voxbone : A EU based provider of worldwide VoIP virtual numbers
Networks: Software Service
Camfrog : Camfrog Video Chat uses a proprietary system with instant messaging to do multi-user audio and video.
FWD (formerly Free World Dialup) : A free SIP-based VoIP network.
Gizmo_Project : Gizmo Project uses your internet connection (broadband or dial-up) to make calls to other computers, phones and mobiles.
Paltalk : A
proprietary freeware VoIP system which uses a messenger-like client for
video, voice and text chat. Also offers interoperable #REDIRECT Instant Messenger (IM) with #REDIRECT AOL/AIM, #REDIRECT Yahoo Messenger, #REDIRECT MSN Messenger and #REDIRECT ICQ using the Paltalk client.
Asterisk PBX :
The popular Linux-based open source software PBX switch. It is known to
compile and run on GNU/Linux for PPC along with OpenBSD, FreeBSD, and
Mac OS X Jaguar.
Ekiga : The popular
Linux-based open source softphone which supports a wide variety of
video and audio codecs. Version 1 supported only H.323, while version 2 supports H.323 and SIP.
KCall is an open source Linux softphone using Qt toolkit libraries.
IP Multimedia Subsystem :
architectural model (with several SIP extensions), used by the
traditional telecommunications industry to develop systems to replace
the current circuit switched network with a NGN network.
OpenH323 : An implementation of the H.323 protocol released under the MPL license. It is used as the basis of several other VoIP applications including Ekiga and GnuGK. A new version of OpenH323 called OPAL is available that supports both H.323 and SIP
OpenWengo : Voip-application published under GNU GPL license
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