Comparison of VoIP software
This is a comparison of Voice over IP (VoIP) software used to conduct telephone-like voice conversations across Internet Protocol (IP) based networks. For residential markets, VoIP phone service is often cheaper than traditional public switched telephone network (PSTN) service and can remove geographic restrictions to telephone numbers, e.g. have a PSTN phone number in a New York area code ring in Tokyo.
For businesses, VoIP obviates separate voice and data pipelines, channelling both types of traffic through the IP network while giving the telephony user a range of advanced capabilities.
Softphones are client devices for making and receiving voice and video calls over the IP network with the standard functionality of most "original" telephones and usually allow integration with IP phones and USB phones instead of utilizing a computer's microphone and speakers (or headset). Most softphone clients run on the open Session Initiation Protocol (SIP) supporting various codecs. Skype runs on a closed proprietary network but additional PBX software can allow a SIP based telephone system to connect to the Skype network. Online "Chat" programs now also incorporate voice and video communications.
Other VoIP software applications include conferencing servers, intercom systems, virtual FXOs and adapted telephony software which concurrently support VoIP and PSTN like IVR systems, dial in dictation, on hold and call recording servers.
Some entries below are Web-based VoIP; most are standalone applications.
General softphone clients
|Program||Operating systems||License||Costs||Protocols||Codecs||Encryption||Max conference peers||Other capabilities||Latest release|
|Avaya Application Server 5300 Soft Client||Windows||Proprietary||?||SIP, RTP,||Unknown||TLS, SRTP||Unknown||2.0 (2010)|
|AudioCodes MobilityPLUS||Windows, Android, iOS||Proprietary||?||SIP, RTP, XMPP, STUN, ICE||G.722 wideband, G.711a, G.711u, iLBC, G.729a, SILK, GSM, VP8, H.264, Opus||TLS, SRTP||Unknown||Voice, video, IM, Group chat, content sharing, SMS and MMS over IP services, native and social network contacts integration, incoming call/IM push notifications.||(2014)|
|Blink||GNU/Linux, Mac OS, Windows||Mixed (free software versions under GNU GPLv3 + shareware versions under gplv3 with exception of including proprietary code)||Windows and Linux are free, OSX version is available for a fee in Mac App Store, source code is freely available||ICE, SIP, MSRP, RFB (VNC), XCAP||Opus, speex, G.722, GSM, iLBC, PCMU, PCMA||TLS, SRTP, ZRTP for all versions, OTR/SMP for OSX version only||Unlimited||IM, File Transfer, Desktop Sharing, Multi-party conference, Wideband||Pro:Template:Latest stable software release/Blink (software) Qt:Template:Latest stable software release/Blink Qt|
|Cisco IP Communicator||Windows, Android||Proprietary||?||SCCP (Skinny), SIP, TFTP||G.722 wideband, G.711a, G.711u, iLBC, G.729a, G.729ab||SRTP||Unknown||Call Recording, Silent Monitoring, Multiple lines and directory numbers, Configurable speed dial, Calling name and number display, Call Waiting, Call Forward, Call Transfer, Three-Way Calling (conference), Call Park, Call Pickup, Redial, Hold, Barge, Callback, Extension Mobility, Message waiting indicator, iDivert, Meet Me conferencing, Group Pickup, Do Not Disturb||7.0.6 (Jan 2011)|
|Ekiga||Linux, Windows, OpenSolaris||GPL||Free||SIP, H.323, STUN, Zeroconf, XMPP, RTP||H.263, H.264/MPEG-4 AVC, Theora, iLBC, Speex, SILK, GSM, ...||No||Unknown||Video, IM, LDAP, Call Forwarding, Call Transfer, Auto-answering, PC to phone, phone to PC, Multiple accounts, USP support, Message waiting indicator, SIMPLE-based presence etc.||4.0.1 (February 21, 2013[±])|
|Empathy||Linux||GPL||Free||SIP, XMPP (Jingle), ICE (STUN/TURN), Zeroconf||Unknown||No||Unknown||IM, multi-user A/V, collaborative applications||3.16 (March 25, 2015[±])|
|Eyeball Chat||Windows||Proprietary||Free||SIP, STUN, ICE, XMPP||Unknown||Yes||5||IM, Conferencing, Voice, Video and SIMPLE based presence||Windows 3.2 (2009)|
|eyeBeam||Windows||Proprietary||?||SIP / SIMPLE||Unknown||TLS, SRTP||6 party audio; 3 party video||Voice and Video calling; IM; Import Microsoft Outlook Contacts; USB Support; Call Recording and Conferencing||22.214.171.124 (March 2010)|
|Google+ Hangouts||Linux, Windows, Mac OS X, Android, iOS||Proprietary (using libjingle)||Free||XMPP||Unknown||SRTP||10||Video, chat, screen sharing, with additional tools available as "Hangout Apps".||Google Chrome Web Store extension
2013.626.1614.1 (July 9, 2013 ) [±] 
|IBM Sametime||Linux, Mac OS X, Windows, mobile||Proprietary||?||SIP, SIMPLE, T.120||H.323||TLS||Unknown||IM, File transfer, Voice, Presence, Server stored contact list, HTTP tunneling, plugins, embedable in Lotus Notes||8.5.2 (08. May 2011)|
|iCall||Linux, Mac OS X, Windows, iOS, Android||Proprietary||Free||SIP, AIM, ICQ, XMPP||Speex, CELT, WebM||TLS, ZRTP||Unlimited||Video, file transfer, PC to phone, phone to PC, IM (MSN, AIM, ICQ, Yahoo!, XMPP, Google Talk), Voicemail||7.1.522|
|Jitsi||Linux, Mac OS, Windows (all java supported). Experimental Android builds are also available.||LGPL||Free||SIP/SIMPLE, XMPP/Jingle STUN ICE, TURN||SILK, G.722, Speex, Opus, G.711 (PCMU/PCMA), iLBC, GSM, G.729, H.264, H.263, VP8||ZRTP, SRTP, TLS||Unknown||Text messaging, audio/video telephony, IPv6 (often broken, P2P not supported), call recording, 64-bit||2.8 (build.5426) (March 19, 2015[±])|
|KPhone||Linux (KDE)||GPL||Free||SIP, STUN, NAPTR/SRV||Unknown||SRTP||Unknown||Video, voice, IM, external Sessions, IPv6 support for UDP||1.2 (November 2008)|
|Linphone||Linux, Windows, Mac OS, Android, iPhone, BlackBerry||GPL||Free||SIP||Speex, Opus, G711, GSM, G.722, VP8 (WebM), H263, MPEG4, Theora and H264 (plugin)||TLS, SRTP, ZRTP||Unknown||Video, IM, STUN, IPv6 (disables IPv4 support when enabled, P2P supported only by version 3.5.1-2)||3.7.0 (20 Feb 2014)|
|Messages||Mac OS X||Proprietary||?||SIP AIM ICQ XMPP||H263, H264||Unknown||Unknown||Integrated, PBX independent||7.0 July 25, 2012|
|MicroSIP||Windows||GPL||Free||SIP, STUN, ICE, SIMPLE||Speex, iLBC, GSM, G.711, G.722, G.729, SILK, Linear PCM||TLS, SRTP||Unknown||Video, voice, IM and Presence||3.6.3 (May 29, 2014)|
|Mirial Softphone (Mirial s.u.r.l.)||Windows 2000/XP/2003/Vista/7 (including 64bit versions), Mac OS X (x86)||Proprietary||not free||SIP, RTSP||H.323||DTLS-SRTP||Unknown||H.264 Full-HD 1080p video rx/tx, Two independent lines supporting Call Control and 3-Party videoconference in Continuous Presence, G.722.1/C wideband audio, Call recording/export, DV/HDMI/Component capture, Presentation (H.239, RFC-4796), Encryption, Far End Camera Control, GPU accel (D3D and OpenGL)||7.0.24 (May 26, 2010) discontinued|
|Mumble||Linux, Mac OS X, iOS, Windows, Android||BSD||Free||Unknown||CELT, Speex, Opus||TLS and OCB-AES128||No max (limited only by server bandwidth and memory)||Chat with (limited) embedded HTML, Automatic Gain Control, Access Control Lists for user management, Customizable In-Game Overlay, Directional Audio, Plugin Support, Nested Channels, Echo cancellation, Logitech G15 support, Push-To-Talk||1.2.8 (August 8, 2014)|
|Nymgo||Windows, Android, iOS||Proprietary||Free||SIP, RTP and RTCP||Unknown||Yes||No||Address Book integration, Call recording/export, Mute, On Hold, Caller ID definition||4.2.9 (March 2013)|
|oovoo||Mac OS X, iOS, Windows, Android||Proprietary||Free||SIP, RTP and RTCP||Unknown||Yes||No||Address Book integration, Call recording/export, Mute, On Hold, Caller ID definition||4.2.9 (March 2013)|
|Phoner||Windows||Proprietary||Free||SIP, TAPI, CAPI||Unknown||TLS, SRTP, ZRTP||8||Conferencing, call redirection, call recording||2.97 (17 April 2015[±])|
|PhonerLite||Windows||Proprietary||Free||SIP||Unknown||TLS, SRTP, ZRTP||8||Conferencing, call redirection, call recording||2.24 (17 April 2015[±])|
|QuteCom||Linux, Mac OS X, Windows XP/2000||GPL||Free||SIP||G.711, G.729, iLBC, AMR-NB, G.722, Speex, AMR-WB (G.722.2), H.263, H.263+, H.264, Dirac||SRTP, but key exchange via Everbee key Exchange which is not a Standard||Unknown||Video, IM (MSN, AIM, ICQ, Yahoo!, XMPP, Google Talk), voicemail, wengo to phone, conferencing.||2.2.1 (June 22, 2011) [±]|
|Revation Communicator||Windows, Mac OS X||Proprietary||?||Proprietary||G.722, G.711, VP8, Opus||TLS and SRTP||No max (limited by server mixing services)||Secure Multi-Party Chat/Instant Messaging, Presence, VoIP, Video, File Transfer, Desktop Sharing||7.0 (June 2014)|
|SFLphone||Linux||GPL3||Free||SIP, RTP, IAX2, STUN per account, SRV||Audio: Opus, Speex, G.722, G.711, GSM, VP8, G.729, iLBC. Video: H.264, H.263, VP8, MPEG-4||Voice encryption (SRTP with SDES or ZRTP) and signaling encryption (TLS), Multiple realms authentication mechanism||Unlimited||Gnome/KDE client, address book, multiple accounts, unlimited number of calls, call transfer, call hold/unhold, call recording, Multi-way conferencing||1.4.1 (September 2014)|
|Skype||Linux, Mac OS X, Windows 2000/XP/Vista/7/Mobile (no longer supported), BREW, Windows Phone , Android, iPhone, PSP||Proprietary||Free||Proprietary P2P protocol [a]||SILK||Advertises proprietary encryption which is not considered secure.||25 starting with version 126.96.36.199. 10 with 2.x||Conferencing, video, file transfer, voicemail, Skype to phone, phone to Skype, additional P2P extensions (games, whiteboard, etc...); depending on platform.|
|Spikko||Windows 2000/XP/Vista/7/Mobile, iPhone,||Proprietary||Free||SIP||Unknown||Yes||8||Conferencing, voicemail, PC to phone, phone to PC, Free international phone numbers, address book integration;||Dec 2010|
|TeamSpeak||Linux, Windows, Mac OS X, FreeBSD, Android, iOS||Proprietary||Free||Unknown||CELT, Speex, Opus||Yes||32 unlicensed / 512 with Non-Profit License / 2000||Simultaneous Server Conferencing with Tabs, 3D Sound Effects, Scalable Permissions System, Firewall Friendly File Transfers, In-Game Overlay for DirectX & OpenGL Games, Global Public Server List, Plugin System||3.0.13|
|TeamViewer||Linux, Windows, Mac OS X, iOS, Android||Proprietary||Free (personal use only)||Unknown||Unknown||AES256||Unknown||Unknown|
|Telephone||Mac OS X 10.10.2||BSD||Free||SIP, STUN, ICE||Unknown||No||Unknown||Address Book integration||1.1.4 (March 6, 2012)|
|Toktumi Unlimited / Line2 Pro||Windows XP/Vista/7, Mac OS X, iOS, Android||Proprietary||Free||Proprietary with SIP core||Unknown||Unknown||20||Conferencing, voicemail, caller ID, call-waiting, address book integration; auto-attendant, call-forwarding||Windows: August 2010 / OS X: October 2010|
|Tru App||Windows 2000/XP/Vista/7, Mac OS X, Linux
iOS, Android, Symbian, BlackBerry OS,
|Proprietary||Free||SIP, XMPP||Unknown||Unknown||Unknown||Chat, file transfer, voicemail, inbound numbers, integration with GTalk, Microsoft Live, Skype|
|Twinkle||Linux||GPL||Free||SIP||G.711 A-law μ-law, G.726, GSM, iLBC, Speex narrow wide ultrawide||SRTP, ZRTP||3||Conferencing, chat, file transfer, Firefox integration, call redirection, voicemail, support of VoIP-to-Phone services||1.4.2 (February 25, 2009[±])|
|Ventrilo||Mac OS X, Windows||Proprietary||Free||Unknown||Unknown||No||8||Conferencing, chat, text-to-speech||3.0.8|
|Viber||Linux[b], Mac OS X[b], Windows[b], Android, Bada, BlackBerry OS, iOS, Series 40, Symbian, Windows Phone||Proprietary||?||Unknown||Unknown||Unknown||Unknown||Varies by platform: Text, picture and video messaging on all, voice calling only on iPhone, Android and Microsoft's Windows Phone|
|Voice Operator Panel||Windows 2000/XP/Vista||Proprietary||?||SIP, RTP||Unknown||Unknown||Unknown||Call forwarding, Call transfer, Call recording, Presence, Outlook integration, Windows Messenger/MSN/Live integration, CRM, Built-in web browser & e-mailer, LDAP, APS.||1.3.2|
|X-Lite||Mac OS, Windows||Proprietary||Free||SIP, STUN, ICE, TURN||H.263, H.263+, G.711, iLBC, Speex||No||3||VoIP over WiFi / 3G / 4G, Video, Instant Messaging / Presence (SIP SIMPLE), Call Waiting, Call Hold, Call Forwarding, Voice Mail / Messaging Waiting Indication, 3 Way Conferencing, Contacts integration, Background Noise Reduction (BNR), Automatic Gain Control (AGC)||Windows and Mac OS: 4.7 (2014)|
|Yahoo! Messenger||Mac OS (8, 9, X), Windows, (Linux/FreeBSD version not VoIP capable)||Proprietary||Free||SIP (using TLS) and RTP (media)||Unknown||Unknown||Unknown||Video, file transfer, PC to phone, phone to PC||Windows: 188.8.131.52 / May 31, 2012
Mac: 3.0.1 / July 20, 2011
Linux: 1.0.6 / September 2003
SunOS 5.7: 0.99.17-1 / September 2003
Solaris 8: 1.0.4 / September 2003
FreeBSD 4/5: 1.0.4 / September 2003 iOS: 2.2.6/ July 12, 2012
|Yate Client||Linux, Mac OS, Windows||GPL||Free||SIP, IAX, XMPP, H.323||G.711a, G.711u, GSM 06.10, iLBC, Speex, G.723, G.726, G.728, G.729||SRTP, Perhaps ZRTP?||Unknown||4.3 2013-01|
|Zfone||Linux, Mac OS X, Windows||Viewable source||(includes time bomb provision)||SIP, RTP||Unknown||SRTP, ZRTP||Unknown||Beta 2008-09-04 (Linux 0.9.224), (Mac OS 0.9.246), (Windows 0.9.206)|
- It is possible to connect by SIP to the Skype network via additional "Skype Connect" PBX software and alternative (SIP) client software/hardware. Neither the Skype software nor the Skype network supports SIP directly
- Viber must be first installed on a mobile phone in order to function on a desktop operating system
Discontinued softphone service
For mobile VoIP clients:
|Program||Operating systems||License||Open Source||Protocols||Codecs||Encryption||Other capabilities||Latest release|
|Acrobits Softphone||Android v2.2+, iOS v4.3+||Proprietary||No||SIP||G.711, G.722, iLBC, GSM, G.729||TLS, SRTP, ZRTP||VOIP over Wi-Fi or 3G iOS only - Push Notifications, video, number rewriting, address book matching, sms for betamax providers and pennytel||Acrobits Softphone (iOS) 5.2, Acrobits Softphone (Android) 3.20|
|iCall Mobile||iOS v4.3+||Freeware / Proprietary||No||SIP AIM ICQ XMPP, Facebook, Yahoo! Messenger, Windows Live.||Speex, CELT, WebM||TLS, ZRTP||VoIP over Wi-Fi or 3G, SMS, Voicemail.||2.0.1 (as of Apr '12)|
|Jajah Mobile Web||Symbian OS, Windows Mobile (version unknown)||web based service, Call back,no download||No||Unknown||Unknown|
|JusTex by Juphoon||iOS v5.1+||Proprietary||No||SIP||PCMA, PCMU, G.722, iLBC, iSAC, Opus, H.264, VP8, H.263||TLS, TCP, UDP, SRTP||JusTex Softphone over Wi-Fi or 3G, HD voice and video call, Multiparty call, conference.||JusTex (iOS) 3.0.1 updated on 13 July. 2014; JusTex (Android) 3.0 updated on 9 July 2014|
|Line2||iOS, Android||Freeware / Proprietary||No||Proprietary with SIP core||Unknown||Unknown||Tri-mode calling (cellular, 3G/4G data, Wi-Fi), SMS over IP, visual voicemail, 20-person conference calls, auto-attendant, call-forwarding||1.0.4 Android, 3.2.1 iOS|
|Media5-fone||iOS, Android||Proprietary||No||SIP||PCMA, PCMU, G.722*, iLBC, iSAC*, G.729*||TLS*, SRTP*||Wi-Fi and 3G/4G data, second call*, conference calls*, HD Voice, Bluetooth* (* Additional fees)||Unknown|
|RedPhone by Open Whisper Systems||Android||GPLv3||Yes||A custom signaling protocol.||Unknown||TLS, SRTP, ZRTP, AES 128||VoIP over Wi-Fi or a data connection. Compatible with Signal on iOS.||1.0.3 on Android|
|Signal by Open Whisper Systems||iOS||GPLv3||Yes||A custom signaling protocol.||Unknown||TLS, SRTP, ZRTP, AES 128||VoIP over Wi-Fi or a data connection. Compatible with RedPhone on Android. TextSecure instant messaging capabilities.||iOS 2.0.3 (April 7, 2015 ) [±]|
|Sipdroid||Android||GPL||Yes||SIP||Unknown||Unknown||Uses Wi-Fi, 3G or EDGE||2.7|
|Tango by TangoME Inc.,||iOS, Android, Microsoft Windows, OS X, Windows Phone||Freeware / Proprietary||Unknown||Unknown||Unknown||Unknown||Wi-Fi VoIP out & in, SMS over IP, call-through & call-back, Voice over IP, Instant messaging, Videoconferencing||Unknown|
|Truphone||Nokia-Symbian, iOS, Android, BlackBerry||Freeware / Proprietary||No||SIP||Unknown||Unknown||Wi-Fi VoIP out & in, SMS over IP, call-through & call-back, connection management, provisioning||Symbian 4.0, iOS 1.11.1|
|Vopium||Symbian, Java ME, Android, BlackBerry RIM, iOS, Windows Mobile 2003 SE and higher||Freeware / Proprietary||No||SIP, MSN, Skype, Yahoo, AOL, ICQ, Google Talk, Facebook & Twitter||GSM||Unknown||Wi-Fi VoIP, GSM call-through, SMS over IP, least cost routing, Synchronisation/back-up of mobile contacts and calendar||2.0|
|Windows Mobile 6||Windows Mobile 6 Professional/Standard||Proprietary||No||SIP to publicly and non-publicly routable servers||Unknown||Unknown||Wi-Fi Mobile VoIP||6.1|
|X-PRO for Pocket PC||Windows Mobile 2003 (earlier versions support Windows PocketPC 2002)||Proprietary, discontinued in April 2007||No||SIP||Unknown||Unknown||Supported devices: AudioVox Maestro, Compaq/HP iPAQ: 365x, 37xx, 385x, 395x, hx4700, Dell Axim X51, X51v, Toshiba e550, e570. iPAQ 545x and Toshiba e7xx are not supported.||2.2|
|Yuilop||Android, iOS, Windows Phone, BlackBerry OS||Freeware||No||XMPP, RTP||iLBC||TLS||VoIP over 3G/4G/LTE and Wifi, SMS, Group chat, Photo sharing, Location sharing, virtual phone numbers||iOS 2.4 (November 26, 2014) [±]
Android 2.0.2 (February 12, 2014[±]
Frameworks and libraries
|Program||Operating systems||License||Protocols/based upon/compatible with||Encryption||Other capabilities||Key and target markets||Latest release|
|Tapioca||Linux||GPL||Telepathy (software)||Unknown||0.3.9 June 12, 2006|
|Telepathy/Farstream||Linux, Mac OS X, Windows||LGPL||SIP, XMPP (Jingle), ICE (STUN/TURN), UPnP||No||Multi-user A/V conferencing, IM, collaborative applications||Mobile devices (Maemo), Linux Desktop||spec 0.17.8 July 24, 2008|
|OPAL||Windows, Linux (including embedded variants), Mac OS X||MPL||SIP, H.323, IAX2, CAPI, VXML||Unknown||Multi-user A/V conferencing, IM, IVR||Softphones, Softswitches, Telephony application servers||3.14.3 October 10, 2014|
|GNU oSIP||Linux, Windows, Mac OS, Android, iPhone, BlackBerry||LGPL||SIP, SDP||Unknown||Multi-user A/V conferencing, IM, IVR||Softphones, Embedded and Mobile devices, Telephony application servers||4.1.0 December 18, 2013|
|Program||Operating systems||License||Protocols/based upon/compatible with||Encryption||Other capabilities||Key and target markets||Latest release|
|3CX Phone System||Microsoft Windows||Proprietary||SIP||TLS, SRTP||Voice and Video IP telephony, Voice and Video conferencing, voice mail and instant messaging||<= 50,000 users||12 (Sep 2013)|
|AS5300||Linux, Windows Server 2003||Proprietary||SIP, UNIStim, MLPP||SSL, TLS,
|Voice and Video IP telephony, Voice and Video conferencing, voice mail and instant messaging||1,000 - 25,000 users||1.0 (Jan 2008)|
|AskoziaPBX||no additional OS required (Linux based)||GPL / Open core||SIP, H.323, IAX, SCCP||No||ISDN, analog, Voicemail, Conferencing, MOH, ACD, IVR, Call forwarding, Call recording||SMEs up to 50 users||2.2.2 (Dec 2012)|
|Asterisk PBX||Linux/BSD, Mac OS X, Solaris||GPL / Proprietary ||SIP, H.323, IAX||TLS, SRTP||VoIP Gateway, voicemail, basic accounting (can be expanded by interface with ODBC-compliant database), billing, conferencing, hot-desking, IVR trees with conditional logic, call queuing, automated call distribution||Enthusiasts, developers, enterprise users (capacity dependent on server design, scalable across multiple servers)||13.0.0 (24 October 2014[±]
11.13.1 (20 October 2014[±])
|Brekeke SIP Server||Linux/Microsoft Windows||Proprietary||SIP||TLS, SRTP||SIP Registrar, SIP Proxy||SIP Service Providers, VoIP service providers, Healthcare, Security||3.3 (Mar 2014)|
|Brekeke PBX||Linux/Microsoft Windows||Proprietary||SIP||TLS, SRTP||Voice and Video IP telephony, Voice and Video conferencing, and voice mail||Hosted service providers, Mid-large enterprise||3.3 (Mar 2014)|
|CallMax Softswitch||Linux||Proprietary||SIP, H.323||SSL, TLS, HTTPS||Integrated billing, IP PBX Platform, Calling card platform, Callshop module, Customer Web Portal.||SIP Service Providers, Residential & Business VoIP providers, Corporate Clients, Other Class 5 softswitch users||3.4.1 (March 2015)|
|CommuniGate Pro||Linux/BSD, Mac OS X, Windows, Solaris, HPUX, AIX||Proprietary||SIP, XIMSS Protocol, XMPP||SSL, TLS||SIP Registrar/Proxy, Authentication, Diameter, RADIUS, ENUM, and many others...||Mobile Operators, ISP's, and SaaS providers||6.0.1 (December 2012)|
|Elastix||Linux||GPL||SIP, IAX, H323, XMPP||No||Unified communication server that also supports chat, mail and fax.||Capacity dependent on server design, scalable across multiple servers||2.4.0 (February 6, 2013)|
|FreeSWITCH||Linux/BSD, Mac OS X, Solaris, Windows||Mozilla Public License||SIP, NAT-PMP, STUN, SIMPLE, XMPP, Google Talk (Jingle), IAX, H.323, MRCP, RSS, Skype||TLS, SRTP, ZRTP||Recording, Voicemail, Conferencing, RADIUS, ENUM, IM Proxy, Streaming, Media gateway, Soft-PBX, IVR (modular)||Large soft-switch users, home PBX users, softphone users||1.4.15 (December 30, 2014[±])|
|FreePBX||Linux, BSD, Solaris||GPL||SIP, IAX, H323, XMPP||TLS, SRTP, ZRTP||Complete PABX Service, based around Asterisk and PHP 5.3. Provides a complete replacement for a legacy non-VoIP phone system. Under current and active development.||Scales from Raspberry PI (3 users) to multiple parallel clusters (10K+ simultaneous calls)||12.0 (October 2014)|
|GNU Gatekeeper||Linux/FreeBSD, Mac OS X, Windows XP/2000/Vista/Windows 7||GPL||H.323||H.235||H.460.18 firewall traversal, Routing, Accounting||video conferencing, VoIP carriers large and small||3.7 (Aug 15, 2014)|
|MediaCore Softswitch||Linux||Proprietary||H.323, SIP, SMPP||SSL, TLS, HTTPS||Dynamic routing mechanism, integrated billing, SIP-H.323 protocol converter, Transcoding - codec converter module, Guardian - revenue assurance module, SBC functionality, full and media proxy, SMS support||Transit VoIP services providers, VoIP wholesale carriers, VoIP termination providers, SMS carriers||4.5 (March 2015)|
|Murmur||Linux/BSD, Mac OS X, Windows||BSD / GPL||CELT, Speex, Opus||TLS||Chat with (limited) embedded HTML, ACLs for user management, Customizable In-Game Overlay, Directional Audio, Plugin Support, Nested Channels||Individuals to Small and medium enterprise (25-5000 users)||1.2.8 (August 8, 2014)|
|Mysipswitch||Linux||BSD||SIP, Ajax||SSL||SIP proxy server which allows the use of multiple SIP accounts with a single SIP login||Individuals||August 2007|
|Objectworld UC Server||Windows XP/2003/2008||Proprietary||SIP||No||IP PBX, personal assistants, IVR, automated phone provisioning, fax server, unified messaging, Outlook, Exchange and Lotus Domino/Notes integration, conferencing, outbound dialing||Small and medium enterprise (25-2000 users)||4.4.2 (May 2009)|
|Kamailio/OpenSIPS (formerly known as OpenSER)||Linux/BSD, Solaris||GPL||SIP, XMPP||No||SIP Registrar/Proxy, Authentication, Diameter, RADIUS, ENUM, least-cost-routing and many others.||SIP Service Providers||4.0.1 (25 April 2013[±])|
|snom ONE (formerly pbxnsip)||Linux/BSD, Mac OS X, Windows||Proprietary||SIP||SRTP||IP PBX, presence indication, IVR, automated phone provisioning, fax server, unified messaging, Outlook, Exchange integration, conferencing, outbound dialing||Small and medium enterprise (25-256 users)||184.108.40.20677 (April 2009)|
|Revation LinkLive||Windows server / Linux||Proprietary||Proprietary||TLS, SRTP||Secure Unified Communications, Presence, Instant Messaging/Chat, VoIP, Video, Desktop Sharing, File Sharing, IVR, PBX, Voicemail, ACD, Email Server||Unified Communications Service Providers||7.0 (June 2014)|
|SIP Express Router (SER)||Linux/BSD, Solaris||GPL||SIP||No||SIP Registrar/Proxy, Authentication, Diameter, RADIUS, ENUM, and many others...||SIP Service Providers||2.0.0 Ottendorf|
|sipXecs IP PBX||Linux||AGPL||Native SIP Call Control, XMPP||TLS, SRTP||Full redundancy (HA), Instant Messaging, Voicemail, User Portal, Admin GUI, plug & play management including phones and gateways, fully featured||Enterprises between 10 and 10,000 users, multi-site||14.04.2 (July 2014)|
|Unison||Linux||Proprietary||SIP, XMPP, IMAP, SMTP, CalDAV||SSL, TLS||Unified messaging, IP PBX, IVR, instant messaging, calendar server, LDAP server, E-mail server||Small and medium enterprise (25-256 users)||3.0 (February 2010)|
|vzRoom||Windows||Proprietary||SIP||SSL, TLS, AES||Instant Messaging/Chat, VoIP, Video, Desktop Sharing, Video Sharing, whiteboard, File Sharing, scheduler, recording||Individual to small and medium enterprise (2-1,000 users)||0.8.8.735 (November 2010)|
|Yate||BSD, Linux, Mac OS, Windows||GPL||SIP, IAX, H.323, ISDN, XMPP (Jabber), Jingle (Google Talk), MGCP, SS7 over IP, Cisco SLT (Signalling Link Transport) (SS7 MTP2 backhaul over IP), SCTP, SCCP, TCAP, MAP CAMEL||SSL, TLS, SRTP||Voice, Video, File Transfer, Data, H323 to SIP Signalling proxy, Instant Messaging, IVR, PC2Phone and Phone2PC gateway, SCCP - GTT routing between networks, Secure Unified Communications, SIP Registrar/Proxy, SIP SBC (session border controller), USSD, Voicemail, VoIP, VoIP to PSTN gateway, Conference server (max 200 voice channels per conference), Call centre server, Prepaid and/or postpaid cards...||Deployed on home servers and large networks with millions of users||5.4 (July 2014)|
- "Skype Connect...". skype.com. Microsoft Corporation Inc. Archived from the original on 2014-11-11. Retrieved 15 November 2014.
- "Ekiga 4.0.1 [STABLE] available". www.ekiga.org. 21 February 2013. Retrieved 2014-05-09.
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