Session Initiation Protocol (SIP) - FAQs, background materials and lists of current work in this field.
Meta Description: [ Session Initiation Protocol ]

BaseVoice - Commercial software development company that produces PBX, router, proxy and application server software.
Meta Description: [ BaseVoice is a VoIP product vendor providing SIP-based solutions for IP communications. ]

Brekeke Software - Products for small to medium sized offices and a server database.

eSMS.com - Provides UK phone numbers which forward calls to SIP.
Meta Description: [ Simwood eSMS provides UK telephone numbers which can forward calls anywhere in the world. We offer every UK prefix from 0800 freephone, through 0870 national rate, to every local area code so you can be associated with any town or city in England, Scotland or Wales. ]

Free IP Call - A proxy service provider with information in English and French.
Meta Description: [ toll free conference calling, free conference call, free conference calling, free call center software, free web conference calling ]

404 Interactive Intelligence, Inc. - Developers of a proxy server. Site contains downloads, documentation and a forum.

LignUp Corp - Applications developer. Products include software PBX's for enterprise and service providers.
Meta Description: [ The LignUp web services based Communications Application Server creates recurring revenue streams with IP telephony, voicemail, unified messaging, and IVR applications and easy development of new or integrated converged web, video, voice and data applications with robust APIs and VoIPlets. ]

Ninetel USA - A USA based proxy service provider and supplier of hardware phones and routers. Site contains call rates and service details.

OpenSER - A branch of the SIP Express Router project, offering an open-source SIP server.
Meta Description: [ OpenSER SIP Server ]

Parrish Systems - Sells off the shelf code and provides a software consultancy service.

PC Phone Review - News and reviews of hardware, software and service providers in the United States.
Meta Description: [ PCPhone Review is dedicated to bringing you the latest information and reviews of VOIP services, Broadband Phone services and everything else that is related to the Internet Phone and VOIP phone market. Users can submit user reviews of VOIP services. There is an extensive FAQ about VOIP services. ]

PROTOS Test Suite - A test-suite to find vulnerabilities in protocol software.

pulver.com - A collection of information on the protocol. Contains news, reports and an IP telephony job noticeboard.

Secure SIP Client - An RFC3261 client running on Win32 and WinCE PDAs supporting voice, video, sRTP and signaling security by TLS.
Meta Description: [ computer network security software internet camera system database pc cillin ]

SIP Compose Group - A working group experimenting and documenting the protocol. Contains various internet technical resources.
Meta Description: [ The Phoenix group, which is the continuation of the Compose project, is a joint INRIA team with LaBRI (CNRS, University of Bordeaux 1 and ENSEIRB), located in Bordeaux. We aim to develop principles, techniques and tools for the creation of multimedia communication services. Our approach covers th... ]

SIP Forum - A membership based forum. Also contains a news board.
Meta Description: [ SIP Forum - a non-profit industry organization that promotes the advancement and adoption of the SIP protocol ]

SIP Made Easy - An introductory tutorial talks about protocol functions, components, message types, how it works and where it is applied.
Meta Description: [ It offers a made easy beginners' tutorial on SIP (Session Initiation Protocol). It talks about user agents, servers, commands, methods, responses, signalling techniques involved in SIP. ]

SIP Wiki - Wiki based resource containing information and links.

SIP411 Directory Services - A Yellow Pages style directory of SIP addresses.
Meta Description: [ SIP411 - 411 Directory Service for SIP ]

Sipcall - A UK based service provider. Also contains hardware related links and protocol white-papers.
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SIPfoundry - An international open source community providing VoIP solutions and technology based on the SIP standard.
Meta Description: [ sipxpbx - the linux sip pbx, Open Source SIP IP PBX ]

SIPquest Inc. - Software component developer for service providers and telecom equipment vendors.
Meta Description: [ FirstHand Technologies mobilizes enterprise unified communications by extending the functionality of IP PBXs and related servers to a variety of smart phones and dual-mode devices over WiFi/cellular networks. Mobile devices are effectively transformed into business telephones and are fully integr... ]

Soft Front - Provides a development environment for software centered around SIP/VoIP technology.
Meta Description: [ SIP connects the future - Softfront supports development of VoIP products and services using SIP technology ]

Tech Invite - Portal containing links to technical information and RFC documentation.
Meta Description: [ Portal for contributing to the promotion and knowledge of SIP and associated technologies, by posting and maintaining white papers ]

The SIP Center - Portal with technical and market resources aimed at commercial developers. Also provides a testbed area for software and proxy development.
Meta Description: [ META DESCRIPTION ]

Voice System - Design, consultancy and development for SIP Express Router (SER) servers.
Meta Description: [ VoIP solutions based on SIP Express Router, design, development and consultancy for VoIP platforms. ]

VoIP News - Information on available technologies and software/hardware product reviews.
Meta Description: [ Keep up to date on the latest news and views about VoIP, IP PBXes, converged networks, Hosted PBXes, and other business telephony solutions. ]

VoIP User - Consumer guide and forum. Also has software phone downloads and links to service providers.
Meta Description: [ The Voice over IP community guide, resource and service centre. VoIP news, reviews and help and support in our forum. ]