SIP Implementations


Below are some implementations in progress or completed. If no URL is shown for the product, the software or hardware is not yet available. Implementations are listed alphabetically by organization.

Not all of the implementations described below are commercial products. Please contact the individual companies and institutions for details. Descriptions were provided by the organization listed.

Many other sites list SIP implementations:

A variety of sources publish reviews of SIP products, e.g., Avaya, Siemens, Zultys

A picture gallery of SIP hardware illustrates some of these.

Test Tools

See also a list of test-related documents such as PICS. sip_scenario can translate SIP call flows into pictures.

Supporting Software

resparse for DNS SRV • smaller SRV parser (Arnt Gulbrandsen, Vijay Gurbani) • dnsjava; RULI (Resolver User Layer Interface); Juphoon ABNF parser

Windows 2000 supports SRV records through its DnsQuery() interface.

Managed DNS for VoIP

SIP Libraries and Stacks

Stacks are written in C/C++ unless otherwise noted. A comparison looks at documentation, functionality and portability.

BaseVoiceColumbia UniversityData ConnectioneXoSIPHelloSoft HelloSIP • Indigo Software (Java) • JuphoonKonnetic (.NET) • Lumisoft (.NET) • MediatrixNetBricksEncore SoftwareNISTOPALOpenSIPStackoSIPPJSIPRADvisionRADvision Express • reSIProcateRNID stack (Delphi 6) • sofia-sipTelogyTrilliumUnicoiU4EAWind River Systems

User Agents (Applications)

See a separate list.

Ethernet Phones

3CombcmCisco (docs) • E-telGrandstreamPingtelSnomTuxScreenWay2Call • Siemens (HiNet LP510)• Siemens optiPoint • Wylus

WiFi Phones

ZyxelSenaoRTX (OEM) •



IP PBX support different SIP phones, not just proprietary Ethernet phones; contain a proxy/registrar with web admin and user interface; a voicemail server; VoiceXML for autoattendant; conference server; possibly a presence server (PA). Not all products contain all of this functionality. 3Cx3Com VCX 7000ArelAsteriskAvayaBrekekeCitelCTLComputer TalkepygiFirstHand TechnologiesFreeSWITCHInteractive Intelligence8x8 IntraswitchNortel MCS-5100 and MCS-5200, Communication Server 1000 Rls. 4 • pbxnsipPBXwarePingtel (sipXpbx)ZultysSiemens HiPath 8000

PSTN Gateways

8x8EpygiKomodoCisco ATA 186 IADSIPURA SPA-2000Interactive IntelligenceMediatrixNueraSonus Networks (GSX) • T&S SoftwareUCLVegastream

Firewalls, NAT traversal and ALGs


Proxies, Registrars and Redirect Servers

The listing also includes vendors of application servers, as these usually include proxy or B2BUA functionality and the boundaries between an application server and proxy are fluid.

3ComAvaya SIP Application Server • BaseVoiceBrekekeCiscoColumbia University sipdFlextronics SoftwareFomineHewlett PackardHotsipHughes Software SystemsIndigoInteractive (support presence and XCAP; also on home routers: SIPatHome) • Meetinghouse Data CommunicationsMy SIPSwitchMicroAppliancesOpenSERObjectSoftwarepartysipPortaOneSailFinSIPfoundry sipXSiptrexSnomSonus Networks (PSX) • T&S SoftwareTerminal TechnologiesWeSIP

3G Systems

BlueSlice Mobile SIP Exchange •

Unified Messaging

Columbia University sipumCTLInteractive IntelligencePingtel

Conferencing and Other Media Servers

Columbia University sipconfCTLFirstHand TechnologiesHughes Software SystemsRADvisionSnom media server •

SIP-H.323 Signaling Gateway

Columbia University ShoutIP • ProfInfoTech




Tellme StudioPingtel


Organization Name of software Contact Type Description
Cisco IOS 12.1(1)T router OS Cisco AS5300 access server, the Cisco 2600 and Cisco 3600 series routers.
ECI IP Application solutions for SIP-enabled networks Application services enhanced calling services, settlement and clearinghouse services, broadband voice services, voice portal services, voice VPN services

CPL, SIP servlet and sip-cgi Implementations

Indigo Software has CPL implementations for both client and server sides (CPL "editor" and CPL "server") that can be coupled to a SIP UA and a SIP proxy, respectively. They are also working on an implementation of SIP-CGI.

Columbia University's sipd server handles sip-cgi and CPL. The sipc UA can upload cgi and CPL scripts.

Institut für Kommunikationsnetze, TU-Wien is developing a service platform based on servlets.

Hughes Software Systems SIP Server provides a CPL engine. "To optimize performance, the SIP server converts raw XML into an internally optimized sequential execution format which results in significant performance gain over executing XML scripts for each service invocation."

Last updated by Henning Schulzrinne