FREE Linux SIP softphone has PBXi functions, IM, 100 addresses, call logs, and calculator. Dial by IP address, SIP address, or number. Works end to end or with proxy, application server, or IP-PBX.

A premium SIP-based User Agent with all the features and functionality of a small business phone system. Open standards-based design allows for maximum network interoperation. PocketPC Version Also

SIP UA for Linux

vPhone lets you see, hear, send files, SMS, MMS and chat with anyone, anywhere in the world - all for FREE. vPhone allows to place high- quality videoconferences and call PC to Phone.

59.NeT, has the difficult task in the global market to reconcile communication quality without leaving aside one single moment: RELIABLE services and LOW COST.

This C++ software provides users\' desktops with real-time multimedia capabilities. The SIP Desktop Agent consists of a comprehensive call control environment supporting IM, presence management, media

IM, STUN

The Teligent SoftPhone is a user-friendly but powerful tool that allows users to turn their personal computer into complete multimedia/telecom centre.

TABLETmedia iFon is the most advanced multi-protocol H.323/SIP softphone for VoIPi, videoconferencing and messaging on mobile devices. Supports G.711i, G.723.1i, G.729A, GSMi, H.261, H.263, AEC, etc.

linux version

H.323/SIP softphone for MS Windows, Linux, and Mac OS X. Supports G.729i, G.711i, GSMi audio codecs. Fully interoperable with ITSPi and software/hardware manufacturers.Allows for calls to PSTNi as well.

IPv6 support claimed

SIP client With support for Multi-line, Mute, Hold, Transfer, Caller ID, Registration, inbound-outbound proxy, conferencing, Call logging. Integrates with myJabber IM. Custom Branding available.

Supports instant messaging, audio and video conferencing, desktop-sharing and Web page pushing; built-in presence; drag-and-drop user actions; buddy list; media mode migration; rebrandable for OEMs

sipXezPhone, is written using C++, wxWidgets, and the sipXtapi API. Currently both Windows and Linux platforms are supported with MAC OS X a clear posibility.

The sipXphone project, formerly known as Pingtel\'s instant xpressa softphone, is a fully functional SIP softphone that runs on Microsoft Windows and Linux.

SIP Phone for Linux

Looks like a very cool SIP phone. Programmable Java interface.

A SIP multimedia client for VoIPi, Video telephony, Video Conference, Screen Collaboration, Whiteboarding, with Universal IM Platform, Phonebook with Presence, Secure speech; 15-day trial

YateClient is a multiprotocol (H.323,SIP,IAX) VoIPi client. It works on Windows and Linux, and is skinable. YateClient is avaible under GPL free license.

This web-based SIP User agent is a thin-client that uses a Web Browser on a PC platform to provide the services provided by the SIP Multimedia PC Client.

Windows PC-based SIP agent that supports traditional telephony communications while providing additional multimedia communications services such as instant messaging, subscriber provisioned incoming...

Mac and PC

Express Talk is a free SIP softphone for Windows. Fully SIP compliant including multiline support (4 lines), hold facility, DNDi, call transfer, NATi traversal and multiple codecs.

Proven PC client for VoIPi, Video telephony, presence, instant messaging, voice mail, etc. SIP and IMSi environments. Converged mobile-PC services such as video sharing, mobile video call.