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Free VoIP Software

Free VoIP Software

Over the previous decade, VoIP (Voice over Web Protocol) applied sciences have seen widespread adoption the world over. Offering communications providers corresponding to voice calls, SMS/MMS textual content messages, fax, and voice messaging, the providers use the Web to move all communications knowledge vice the PSTN (publicly switched phone community). As VoIP has turn into extra well-liked, a standard want for small companies and particular person pc customers is discovering free VoIP software program that doesn’t value a month-to-month or annual charge.

How Does VoIP (Voice over IP) Work?

The rules of creating a standard telephone name on a VoIP community as in comparison with the normal PSTN are very comparable. Putting a telephone name requires signaling, digitizing an analog voice sign, channel setup, and encoding info on the community. As soon as the knowledge from the telephone name is encoded it’s transmitted by way of IP (Web Protocol) packet by way of the Web. A VoIP setup or system makes use of session management and signaling protocols to control the telephone name signaling, preliminary set-up, and the breaking down (or tear down) of telephone calls.

The audio stream of telephone calls and video messaging periods are transported over an IP community utilizing specifically designed media supply protocols which use audio and video codecs to encode audio, voice, and video streams with streaming media. The audio and video codecs employed optimize the media stream relying on the precise software necessities of the VoIP service and out there community bandwidth. Relying on the out there bandwidth, some VoIP implementations depend on decreased community bandwidth and prioritize the suitable choices inside the telephony system to maximise the standard of the telephone calls or different providers leveraged by the service.

How Does VoIP Quantity Portability Work?

Cellular quantity portability (MNP) and Native quantity portability (LNP) laws in america and different developed nations additionally have an effect on corporations that present VoIP providers. Within the mid-2000s (2007), in america, the FCC (Federal Communications Fee) issued path requiring VoIP service suppliers to help the proper of shoppers to maintain a telephone quantity when shifting to a brand new telephone service.

The normal course of to satisfy quantity portability necessities is for the earlier or previous service to take care of a database of telephone numbers and to map the buyer’s quantity to the brand new service. The quantity will probably be maintained for a given timeframe with the previous service and shortly reroute calls to the quantity to the brand new telephone service. All main carriers are required to take care of these porting references to make sure compliance with the FCC mandate.

The requirement for guaranteeing quantity portability provides complexity to VoIP telephone calls. Most VoIP providers depend on a LCR (Least Value Routing) system to makes an attempt to route telephone calls by way of the community path that may “cost” the consumer the least. On account of quantity portability necessities; nevertheless, VoIP service suppliers should confirm what the precise telephone community the telephone quantity is being hosted on first earlier than routing a telephone name (up to now the service prefix a part of the telephone quantity could possibly be used).

VoIP Emergency Name Help

Landlines and extra just lately cell phones are capable of be mapped to a bodily location to be used by emergency responders when a person locations an emergency telephone name. Landlines are mapped to a bodily location maintained by the respective phone firm, whereas most developed nations require cellular suppliers to map the cell telephones gadget to a location utilizing GPS or equal finding providers. When a name is acquired from both of those telephones, the situation and figuring out subscriber info are displayed within the name middle.

For VoIP-based telephones, there’s not a direct linkage between the situation of the caller and the emergency middle. That is additionally true for cable or DSL suppliers who will know the approximate location of the community router and repair tackle, which can not match the locale of the person requiring emergency help. That is very true when an Web connection is used to hook up with a VPN of a company or different entity. For instance, the IP tackle being utilized by the person might belong to the corporate which might not be the identical tackle because the residence. An analogous problem was confronted by the cell phone business till laws requiring figuring out info for emergency calls have been handed in quite a lot of nations.

It’s attainable for a telephone or VoIP gateway to determine itself with a SIP (Session Initiation Protocol) registrar. The affiliation is made utilizing the account credentials with the ITSP (Web Telephony Service Supplier) solely being conscious of the gear getting used or lively. Emergency response providers are offered on this association via an settlement with the end-user. In these instances, the consumer has to register the bodily location of the gear and agrees with the supplier that emergency providers will solely be offered to this handle if the 911 or equal telephone quantity is known as from one of many IP units on the community.

In the USA, one of these emergency service provision is made by VoIP suppliers by way of the E911 (Enhanced 911) system. This technique is predicated on the U.S. Wi-fi Communications and Public Security Act of 1999 and associates a bodily tackle with the VoIP telephone quantity. If the VoIP supplier supplies entry to the PSTN (publicly switched phone community), then they’re required to implement E911. Some suppliers will cross on the price for this service to the end-user; nevertheless, the client maintains the correct to “Opt-Out” of the service if desired. In contrast to the E911 system in place for cell phones (the place the consumer’s location may be dynamically up to date), VoIP E911 requires the buyer keep an up-to-date emergency tackle within the system.

VoIP Safety Considerations

Just like any Web-connected telephone or system, VoIP service suppliers have comparable safety considerations relating to the vulnerability of their community or clients to quite a lot of assaults. These considerations embrace however aren’t restricted to rogue actors compromising voicemail, recording telephone calls, harvesting shopper info by means of using pc malware, and being prone to a denial of service assault. If any consumer account (and even session credentials) are hacked, an attacker could possibly use one other individual or firm’s service at no cost. Even worse, the attacker could possibly place numerous toll or lengthy distance fees which might be mirrored on the unsuspecting social gathering’s invoice.

As soon as an intruder has gained entry to a service, they’re able to benefit from VoIP options that permit the associated visitors to bypass community handle translators and firewalls. Regardless of these personal session border controllers being designed to permit VoIP calls to and from an in any other case protected community, it represents a vulnerability on the Enterprise degree for corporations using VoIP providers. Moreover, to maintain prices low, many VoIP service suppliers won’t present encryption of precise telephone calls making it simpler for rogue actors to intercept or listen in on VoIP conferences or telephone calls if they will achieve entry to the community of one of many two events.

When looking for out a free VoIP service choice, it is very important take these vulnerabilities under consideration. There are requirements out there for safety VoIP providers to incorporate SRTP (Safe Actual-time Transport Portocol) and ZRTP (designed for analog phone adapters and sensible telephones). Alternatively, IPsec an be used (working on the transport degree) by way of using encryption to assist make sure the safety of a person’s communications. Public Safe VoIP is one other widespread choice in free VoIP packages (obtainable underneath the GNU license) that establishes a safe reference to the vacation spot shopper earlier than permitting communications to proceed.

VoIP Timeline

The next is the historic timeline of VoIP know-how and capabilities since inception.
1973 – Danny Cohen and different researchers developed NVP (Community Voice Protocol) designed to hold voice over the ARPANET in real-time.
1974 – IEEE (Institute of Electrical and Digital Engineers) revealed A Protocol for Packet Community Interconnection that may assist type the underlying know-how supporting VoIP use as we speak.
1974 – The primary use of NVP occurred on August 1974 over the ARPANET. This was the very first implementation of VoIP.
1981 – Ipv4 was first outlined in RFC 791. This would offer the underlying construction that the modern-day Web and VoIP providers leverage to offer providers to clients.
1986 – There are a selection proposals for adopting a regular to offer voice providers on ATM-based networks (Voice over ATM) made. The primary commercially obtainable merchandise for network-based voice capabilities are launched.
1991 – Converse Freely is launched as a free, VoIP software. The software program software was created by John Walker and additional improved upon by Brian. C. Wiles.
1994 – Freeware VoIP software, MTALK, was launched to be used on the LINUX working system (OS).
1995 – The primary business Web-based telephone software program is launched by VocalTec. Later this yr, Radvision, Intel, and Microsoft start-up standardization conferences for VoIP applied sciences.
1996 – United States-based TELECOMs petition the American Congress to ban all Web-based telephone know-how.
1999 – The SIP (Session Initiation Protocol) specification is launched (RFC 2543). Throughout this similar yr, the primary open supply PBX (Personal Department Trade) software program is launched by Digium (Asterisk).
2003 – Skype releases their first beta deployment of the extremely common desktop program.
2004 – Thanks partially to the unfold of high-speed Web entry, the variety of VoIP service suppliers considerably expands in most developed nations.
2006 – The VoIP business sees revenues exceed $Three Billion USD for the primary time.
2007 – 2012 – The VoIP business sees common progress of 16.7%. By 2013, your complete business is estimated to see greater than $15 billion in internet income.

What Elements to Contemplate when Selecting VoIP Software?

Earlier than making the choice on what VoIP software program to make use of for both particular person or firm use, there are a selection of things to think about even when looking at free software program choices. These embrace the reliability of the service, options, location, and any up-front or hidden prices with free VoIP software program packages.
Significance of Reliability
Earlier than leaping in and simply choosing a VoIP software program package deal as a result of it’s free, it’s value some research to validate the reliability and frequency of updates of the appliance suite. Simply because a free VoIP package deal acquired nice critiques 5 years in the past doesn’t imply that the software program shall be suitable with one’s present computing working system or supply the options anticipated of a VoIP software package deal in the present day. A number of the freeware choices even have hidden “upsells” that may value extra money than simply subscribing to a commercially out there VoIP answer.
Simply because the software program is free, doesn’t imply that there are not any prices related to the VoIP software program. In an effort to keep away from frustration, its really helpful to analysis and even check out freeware software program packages earlier than going stay within the house or small firm with the open supply options out there to be used.
Most skilled VoIP customers will advocate making an inventory of the options that you simply require in a VoIP software program suite previous to choosing one out. It can shock some shoppers that they don’t essentially want or need all the choices made obtainable to them by way of a VoIP service. Some will probably be required for a enterprise akin to voicemail, video conferencing (not for all), and the power to make a standard telephone name. Different options resembling voicemail to e mail and textual content messaging  could also be thought-about extraneous by some and don’t must be included with a VoIP service package deal until it’s a normal function which doesn’t value extra money in month-to-month service charges.
There are various totally different classes of free VoIP software program packages, together with:

  • Free VoIP Software Telephones
  • Free VoIP Gateways
  • Free VoIP Gatekeepers
  • Free VoIP Proxies
  • Free VoIP Software Improvement Libraries
  • Free VoIP PBX’s

Free VoIP Software Telephones


Ekiga is an H.323 suitable videoconferencing and VOIP/IP-Telephony software that permits individuals to make audio and video calls to distant customers with H.323 hardware or software program (comparable to Microsoft Netmeeting). It helps all trendy videoconferencing options comparable to registering to an ILS listing, gatekeeper help, making multi-user convention calls with an exterior MCU, utilizing trendy Quicknet telephony playing cards, and making PC-To-Telephone calls.

Ekiga was beforehand generally known as GnomeMeeting.


Twinkle is a tender telephone for VoIP communications utilizing the SIP protocol. Individuals can use Twinkle for direct IP telephone to IP telephone communications or in a community utilizing a SIP proxy to route calls.

Along with making primary voice calls, Twinkle additionally supplies the next options:

  • 2 name appearances (strains)
  • A number of lively name identities
  • Customized ring tones
  • Name Ready
  • Name Maintain
  • Three-way convention calling
  • Mute
  • Name redirection on demand
  • Name redirection unconditional
  • Name redirection when busy
  • Name redirection no reply
  • Reject name redirection request
  • Blind name switch
  • Reject name switch request
  • Name reject
  • Repeat final name
  • Don’t disturb
  • Auto reply
  • Consumer definable scripts triggered on name occasions, E.g. to implement selective name reject or distinctive ringing
  • RFC 2833 DTMF occasions
  • Inband DTMF
  • Out-of-band DTMF (SIP INFO)
  • STUN help for NAT traversal
  • Ship NAT maintain alive packets when utilizing STUN
  • NAT traversal by way of static provisioning
  • Missed name indication
  • Historical past of name element data for incoming, outgoing, profitable, and missed calls
  • DNS SRV help
  • Automated failover to an alternate server if a server is unavailable
  • Different packages can originate a SIP name by way of Twinkle, e.g. name from tackle e-book
  • System tray icon
  • System tray menu to shortly originate and reply calls whereas Twinkle stays hidden
  • Consumer definable quantity conversion guidelines


WengoPhone is a SIP telephone that permits customers to talk for free of charge from a pc to different customers of SIP compliant VoIP software program. It additionally permits customers to name landlines, cellphones, ship SMS messages, and to make video calls. None of this performance is tied to a specific SIP supplier and can be utilized with any supplier out there available on the market, in contrast to proprietary options akin to Skype.


Converse Freely is a 100% free Web phone that John Walker, founding father of Autodesk, initially wrote in 1991. After April of 1996, he stopped creating this system. Since then, a number of different Web “telephones” have cropped up everywhere in the world. Nevertheless, most of those packages value cash. Most of them have poor sound high quality, and don’t help Converse Freely’s primary options reminiscent of encryption, the answering machine, or selectable compression.


linphone is a SIP webphone with help for a number of totally different codecs, together with speex.

Linphone is an internet telephone. It permits customers to name their buddies anyplace in the entire world free of charge by way of the Web. The telephone name’s value is the price of the Web connection.

linphone options embrace:

  • Works with the Gnome Desktop beneath Linux, (perhaps others Unixes as nicely, however this has by no means been examined). Linphone can be used beneath KDE.
  • Since model, linphone may be compiled and used with out gnome in console mode, through the use of this system referred to as “linphonec.”
  • Works as merely as a cellphone. Two buttons, no extra.
  • Linphones consists of a big number of codecs (G711-ulaw, G711-alaw, LPC10-15, GSM, and SPEEX). Because of the Speex codec, it is ready to present top quality connections even with sluggish Web connections like 28okay modems.
  • Understands the SIP protocol. SIP is a standardized protocol from the IETF, the group that made a lot of the protocols used on the Web. This guaranties compatibility with most SIP – suitable net telephones.
  • Customers solely want a soundcard to make use of Linphone.
  • Different technical features embrace DTMF (dial tones) help although RFC2833 and ENUM (to make use of SIP numbers as an alternative of SIP addresses).
  • Linphone is a free software program, launched underneath the Basic Public License.
  • Linphone is documented. It has an entire consumer guide that explains all of the consumer must know.
  • Linphone features a sip check server referred to as “sipomatic” that mechanically solutions to calls by enjoying a pre-recorded message.


OhPhone is a H.323 Video Conferencing Program suitable with different H.323 video conferencing packages together with Microsoft NetMeeting.

OhPhone helps full duplex audio and bi-directional video. It requires a full duplex sound card for audio help and a Bt848/878 based mostly video card (utilizing the bktr driver) for video seize.

OhPhone makes use of the OpenH323 and PWLib libraries, which Equivalence Pty developed.

Microsoft NetMeeting

NetMeeting is Microsoft’s free H.323-compliant VoIP software program telephone for Home windows.


SIPSet is a SIP Consumer Agent with a GUI entrance finish that works with the Vovida SIP stack. It may be used as a tender telephone to make and obtain telephone calls from a Linux PC.

The present SIPSet launch implements these options:

  • SIPSet could make calls by way of a SIP proxy.
  • SIPSet can register to obtain calls by means of a SIP proxy.
  • SIPSet could make and obtain calls instantly with one other Consumer Agent.


KPhone is a SIP Consumer Agent for Linux. It implements the performance of a VoIP Softphone however is just not restricted to this. KPhone is licensed beneath the GNU Common Public License. KPhone is written in C++ and makes use of Qt.


Jabbin is an open supply Jabber shopper program that permits free PC to PC calls utilizing VoIP over the Jabber community.

Free VoIP Gateways


isdn2h323 is a Linux based mostly H.323 – ISDN gateway. In the intervening time, the gateway helps the next options:

  • ISDN and H.323 customers can provoke a connection.
  • The variety of simultaneous incoming and outgoing calls is restricted by the variety of out there ISDN channels solely.
  • H.323 customers can specify the opposite get together’s ISDN quantity.
  • The gateway’s administrator can assign an ISDN MSN to a H.323 consumer. This makes it attainable for an ISDN consumer to name a H.323 consumer instantly. The gateway chooses the H.323 consumer id relying on the referred to as ISDN MSN.
  • The gateway discovers an obtainable H.323 gatekeeper and registers with the gatekeeper. It’s potential to specify a number of telephone prefixes that the gateway is answerable for.
  • ISDNs touch-tones (DTMF) are translated to H.323’s consumer enter messages and vice versa.
  • Automated achieve management (AGC)
  • Automated echo compensation (AEC)
  • To keep away from safety issues the gateway gives an choice to limit the IPs allowed to make use of the gateway for an outgoing ISDN name.
  • The standing of the strains and the configuration of the gateway are written to an HTML file.
  • Errors and different info are logged utilizing Linux’s syslog() function.
  • Three H.323 codecs are supported: ALaw, muLaw, and GSM.
  • Least Value Router


PSTNGw is a quite simple PSTN to H.323 gateway program that makes use of the OpenH323 library. It permits H.323 shoppers to make outgoing calls and incoming calls to be routed to a selected H.323 shopper.

PSTNGw makes use of PWLib and the OpenH323 stack from Equivalence Ltd Pty.

SIPRG (SIP Residential Gateway)

The SIP Residential Gateway (SIPRG) is an open supply software based mostly on the Session Initiation Protocol (SIP). The SIPRG is an IP Telephony Gateway that permits a SIP Consumer Agent to make and obtain calls between the Public Switched Phone Community (PSTN) and a SIP-based community similar to VOCAL.

The SIPRG was developed with the VOVIDA SIP stack model and makes use of a QuickNet LineJACK card to attach an Analog phone line. At present, it helps solely a single LineJACK card and is subsequently a single-line gateway.

Free VoIP Gatekeepers

OpenH323 Gatekeeper – The GNU Gatekeeper

The OpenH323 Gatekeeper is a full featured H.323 gatekeeper that’s out there free of charge beneath GPL license. It’s based mostly on the Open H.323 stack. Each elements collectively type the idea for a free IP telephony system (VOIP).

OpenH323 Gatekeeper at present helps Linux, Microsoft Home windows, FreeBSD, Solaris, and MacOS X.


OpenGatekeeper is an Open Supply H.323 Gatekeeper based mostly on the work finished by the OpenH323 undertaking.

OpenGatekeeper runs on Linux, FreeBSD, and Win32 platforms.

OpenGatekeeper helps all the essential options of an H.323 Gatekeeper corresponding to registration, admissions and entry management, tackle translation, and bandwidth monitoring and management.

OpenGateKeeper additionally helps many superior options similar to:

  • Gatekeeper routed calls
  • Help of H.323v2 alias varieties (social gathering quantity, URL, transport id and e-mail tackle)
  • Help for gateway prefixes
  • Registration and name exercise logs
  • Neighbor gatekeeper database
  • Registration time to stay

Free VoIP Proxies


Partysip is a SIP proxy server. It’s a plugin oriented program with registration, authentication, and routing capabilities.

Partysip is a modular software the place capabilities are added and eliminated via plugins. This system comes with a number of GPL plugins. At this step, partysip and its plugins might be used as a ‘SIP registrar,’ a ‘SIP redirect server,’ and a ‘SIP stateful proxy server.’

siproxd – SIP proxy/masquerading daemon

Siproxd is a proxy/masquerading daemon for the SIP protocol. It registers SIP shoppers on a personal IP community and rewrites the SIP message our bodies to make SIP connections attainable by way of a masquerading firewall. It permits SIP shoppers (like kphone, linphone) to work behind an IP masquerading firewall or router.

Softphones (Voice over IP) use SIP (Session Initiation Protocol) to provoke communication. By itself, SIP doesn’t work by way of masquerading firewalls because the transferred knowledge incorporates IP addresses and port numbers.

Load Balancer Proxy

The Load Balancer is a quite simple proxy that’s helpful in SIP-based VoIP installations the place there are a number of ingress proxy servers. The Load Balancer permits pooling these servers, thereby eliminating the necessity to stability consumer calls for for connectivity by way of a sophisticated provisioning algorithm.

All customers can ship their INVITEs and REGISTERs to the identical SIP URI and the Load Balancer will assign ingress proxy servers dynamically to every transaction. On this method, the visitors load is balanced over a pool of proxy servers based mostly on the real-time demand for providers.

STUN Server

The STUN (Easy Traversal of UDP by means of NATs (Community Handle Translation)) server is an implementation of the STUN protocol that permits STUN performance in SIP-based methods. The STUN server tar ball additionally embrace a shopper API to allow STUN performance in SIP endpoints. As well as, there’s a command line Unix shopper and a graphical home windows shopper that examine what sort of NAT the consumer is utilizing.

STUN is an software layer protocol that determines the general public IP and nature of a NAT gadget that sits between the STUN shopper and STUN server.

The present model of the code helps most of RFC 3489 besides the power to get OTPs from the server.

Free VoIP Software Improvement Libraries


Yate (But One other Telephony Engine) is a subsequent era telephony engine. Whereas at present targeted on Voice over Web Protocol (VoIP) and PSTN, its energy lies in its potential to be simply prolonged. Voice, video, knowledge, and immediate messaging can all be unified underneath Yate’s versatile routing engine, maximizing communications effectivity and minimizing infrastructure prices for companies.

Yate can be utilized to construct a:

  • VoIP server
  • VoIP shopper
  • VoIP to PSTN gateway
  • PC2Phone and Phone2PC gateway
  • H.323 gatekeeper
  • H.323 a number of endpoint server
  • H.323<->SIP Proxy
  • SIP session border controller
  • SIP router
  • SIP registration server
  • IAX server and/or shopper
  • IP Telephony server and/or shopper
  • Name middle server
  • IVR engine
  • Pay as you go and/or postpaid playing cards system

The software program is written in C++ and helps scripting in numerous programming languages (resembling these supported by the at present carried out embedded PHP, Python, and Perl interpreters) and even any Unix shell. The PHP, Python, and Perl libraries have been developed and made out there with a purpose to ease improvement of exterior functionalities for Yate.

Yate is manufacturing prepared software program and is definitely extensible.

Yate is licensed underneath the GPL with an exception for linking with OpenH323 and PWlib (licensed beneath MPL).


PJSIP is an open supply SIP stack supporting many SIP extensions/options, with the next key advantages:

Extraordinarily moveable

Write the appliance as soon as and it runs on many platforms (all Home windows flavors, Home windows Cellular, Linux, all Unix flavors, MacOS X, RTEMS, Symbian OS, and so on.)

Very small footprint

With lower than 150KB for full SIP options, PJSIP is right not just for embedded improvement the place area is expensive, but in addition for basic purposes the place smaller measurement means shorter obtain time for customers.

Excessive efficiency

This implies much less CPU energy requirement and extra SIP transactions/calls may be dealt with per second.

Many options

Many SIP options/extensions comparable to a number of usages in dialog, occasion subscription framework, presence, on the spot messaging, name switch, and so on. have been carried out within the library.

In depth SIP documentation

There can by no means be sufficient documentation, so fellow builders are supplied with lots of of pages value of documentation.

PJSIP additionally options extensions similar to:



PJMEDIA is a complementary library for PJSIP to construct full, full featured SIP consumer agent purposes corresponding to softphones/hardphones, gateways, or B2BUA.



PJLIB-UTIL is an auxiliary library offering help for PJMEDIA and PJSIP. A number of the features/elements on this library are small footprint XML parsing, STUN shopper library, asynchronous/caching DNS resolver, hashing/encryption features, and so forth.



A small footprint, excessive efficiency, extremely moveable abstraction library and framework that PJSIP and PJMEDIA use.


PJLIB is about the one library that PJLIB-UTIL, PJMEDIA, and PJSIP ought to rely upon, because it offers full abstraction not solely to Working System dependent options, however additionally it is designed to summary LIBC and offers some helpful knowledge buildings too.

Vovida Open Communication Software Library (VOCAL)

The Vovida Open Communication Software Library (VOCAL) is an open supply venture focused at facilitating the adoption of VoIP within the market. VOCAL offers the event group with software program and instruments wanted to construct new and thrilling VoIP options, purposes, and providers. The software program in VOCAL features a SIP based mostly Redirect Server, Function Server, Provisioning Server, Coverage Server, and Marshal Proxy together with protocol translators from SIP to H.323 and SIP to MGCP. Our hope is that these modules will act as constructing blocks to assist create higher, quicker, and stronger VoIP methods.

The GNU oSIP Library

oSIP is an implementation of SIP.

SIP (Session Initiation Protocol) is described by the RFC3261. This library goals to offer multimedia and telecom software program builders with a simple and highly effective interface to provoke and management SIP based mostly periods of their purposes. SIP is an open normal alternative from IETF for H.323.

JVOIPLIB (Jori’s Voice over IP library)

JVOIPLIB is an object oriented Voice over IP (VoIP) library written in C++.


eXosip is a brand new library based mostly on oSIP. It incorporates a excessive layer simpler to make use of for implementing SIP Finish level.

eXosip is a library that hides the complexity of utilizing the SIP protocol for mutlimedia session institution. This protocol is especially for use by VoIP telephony purposes (endpoints or convention server), however could be additionally helpful for any software that needs to determine periods like multi-player video games.

Free VoIP PBX Software


Asterisk is an entire PBX in software program. It runs on Linux and offers all the options anticipated from a PBX and extra. Asterisk does voice over IP in three protocols and may interoperate with virtually all requirements based mostly telephony gear utilizing comparatively cheap hardware.

Asterisk offers Voicemail providers with Listing, Name Conferencing, Interactive Voice Response, and Name Queuing. It has help for three-way calling, caller ID providers, ADSI, SIP, and H.323 (as each shopper and gateway).

Asterisk wants no further hardware for Voice over IP. For interconnection with digital and analog telephony gear, Asterisk helps a lot of hardware units, most notably all the hardware that Asterisk’s sponsor, Digium, manufactured. Digium has single and quad span T1 and E1 interfaces for interconnection to PRI strains and channel banks in addition to a single port FXO card and a one to four-port modular FXS and FXO card.

Additionally supported are the Web Line Jack and Web Telephone Jack merchandise from Quicknet.

Asterisk helps a variety of TDM protocols for the dealing with and transmission of voice over conventional telephony interfaces. Asterisk helps US and European commonplace signaling varieties utilized in commonplace enterprise telephone methods, permitting it to bridge between subsequent era voice-data built-in networks and present infrastructure. Asterisk not solely helps conventional telephone gear, it enhances them with further capabilities.

Utilizing the Inter-Asterisk eXchange (IAX) Voice over IP protocol, Asterisk merges voice and knowledge visitors seamlessly throughout disparate networks. Whereas utilizing Packet Voice, it’s attainable to ship knowledge akin to URL info and pictures in-line with voice visitors, permitting superior info integration.

Asterisk offers a central switching core, with 4 APIs for modular loading of telephony purposes, hardware interfaces, file format dealing with, and codecs. It permits clear switching between all supported interfaces, permitting it to tie collectively a various combination of telephony techniques right into a single switching community.

Asterisk is primarily developed on GNU/Linux for x/86. It’s recognized to compile and run on GNU/Linux for PPC together with OpenBSD, FreeBSD, and Mac OS X Jaguar. Different platforms and requirements based mostly UNIX-like working methods ought to be fairly straightforward to port for anybody with the time and requisite talent to take action. Asterisk is out there within the testing and unstable Debian archives and Mark Purcell maintains it.

GNU Bayonne

GNU Bayonne, the telephony server of GNU Telephony and the GNU undertaking, provides a free, scalable, media unbiased software program surroundings for improvement and deployment of telephony options used with present and subsequent era phone networks.

GNU Bayonne helps IVR scripting utilizing hardware from Voicetronix, Dialogic, Aculab, CAPI drivers, and Quicklink drivers underneath GNU/Linux. Bayonne performs script pushed IVR purposes written in GNU Bayonne’s native scripting language, in addition to accesses, converts, and performs audio from distant URLs.


FreeSWITCH is an open supply telephony software written in C, constructed from the bottom up, and designed to reap the benefits of as many present software program libraries as potential. FreeSWITCH makes it attainable to construct an open supply PBX system or an open supply voip switching platform in addition to unite numerous applied sciences comparable to SIP, H.323, IAX2, LDAP, Zeroconf, XMPP / Jingle and so on. FreeSWITCH may also be used to interface with different open supply PBX techniques resembling Asterisk, GNU Bayonne, or OpenPBX.

OpenPBX is an open Supply Personal Department Change System (PBX) in software program for the Linux Working system. is licensed beneath the GNU Common Public License or GPL.

Different VoIP Software


Fobbit permits Artistic VoIP Blaster hardware units for use beneath NetBSD, Linux, and Microsoft Home windows. It permits calls to be made to different Fobbit customers with out the necessity for the unique Artistic Labs software program, and works from behind firewalls and NAT.


CPhone is a cross-platform GUI for the OpenH323 VoIP libraries.


SIPTiger is an internet based mostly provisioning utility for Cisco’s line of 7960 and 7940 Session Initiation Protocol (SIP) IP telephones and Cisco SIP Proxy Servers (CSPS). This utility is beneficial for anybody deploying Cisco 7960/7940 SIP IP Telephones.

SIPTiger model 2.Three.1 is now obtainable with expanded performance and a number of other bug fixes. See the readme file for extra particulars.

Cisco 7960/7940 SIP IP telephones and Cisco SIP proxy servers each depend on a set of configuration information, which SIPTiger can parse and format right into a consumer pleasant net based mostly Graphical Consumer Interface (GUI). After these information are modified, the affected SIP telephones can then be remotely reloaded to permit the modifications to take impact. SIPTiger additionally helps administrative-level name forwarding configuration.