Asterisk 
Asterisk is basically the grand daddy of all open source PBX and VoIP strategies and continues to work as the gold standard. As the top open supply telephony platform along with a tremendous element prospect lists which just continues to develop each year, the Asterisk tool system is employed by not just a mass quantity of setups across the planet, a lot of the providers on the list of ours have both started with or perhaps are based completely off of the Asterisk motor.
Filled with the conventional PBX features which includes an active voice response menu, instant call distribution, conference calling, as well as the typical voicemail, Asterisk can help you make some pc right into a communications server. Supported by Digium, the software program is totally free as well as open source. To help get you started, Asterisk supplies fresh web classes, online training programs, as well as an Asterisk Definitive Guide hand from O’Reilly Press. Asterisk could nearly be regarded as the go to platform with regards to building the VoIP of yours, UC or PBX system.
Elastix
Initially based off the Asterisk platform, Elastix provides open source single communications server program which includes an IP PBX, IM, email, faxing as well as collaboration functionality. With a solid focus on the entrepreneurial sector, the device is entirely free for personal or commercial use.
The project has additionally brought in characteristics from other open source tasks such as Postfix, Openfire, HylaFAX, and FreePBX to ro
und out every one of the UC offerings out there.
General, Elastix is designed to pull in the best characteristics of other tasks and Asterisk, all under one easy-to-use screen. Elastix boasts support for a broad range of hardware such as Snom, Yealink, Yeastar, Dinstar, and Digium . Elastix was among the first distributions which incorporated a call center module with a predictive dialer and goes on to give a strong remedy, once again free under the GNU General Public License.
Since writing this post, it’s come to the attention of ours that Elastix just appears to provide up to eight complimentary SIM calls for aproximatelly twenty five users.
FreeSWITCH
FreeSWITCH was additionally initially depending on the Asterisk platform and was developed as well as created by 3 of the initial designers of the Asterisk platform, Anthony Minessale II, Brian West, and Michael Jerris. With a focus on modulatory, cross-platform support, stability and scalability, FreeSWITCH provides one of the more adaptable platforms to construct your very own UC suite around.FreeSWITCH supports SIP, H.323 as well as WebRTC to control the newest developments of the technology, and very easily incorporate and interface along with other any of the various other widely used open source PBX platforms offered.
In order to bring down the intricacy of a method, FreeSWITCH utilizes readily accessible software program libraries that will conduct the required features for the system of yours to the office. FreeSWITCH provides the typical calling functions as well as gives some extras as speech recognition as well as synthesis as well as PSTN interfaces for digital circuits and analog.
PBXInAFlash
PBXInAFlash is designed to really make it possible to set up the PBX server of yours, as the title puts it, in a flash. The project has collected everything in a single put that users will have to produce the PBX system of theirs within under an hour, one that employs the CentOS Linux operating system, which includes an Apache web server, SendMail server, and MySQL database server along with firewalls as well as required protocols. The device likewise provides owners the option of Asterisk 1.8, ten, eleven or maybe FreePBX 2.9, 2.10 or perhaps 2.11.
Owners likewise have the choice to select from dozens of add ons to really custom tailor the device with useful capabilities including automated backups, Caller ID lookup services, SSL keys, Google Voice integration, text-to-speech functionality, and fax assistance simply to name just a few. Everything is actually created to be simple, and add ons may be fitted with one click in under a second. With the main goal of no bugs and no bloat, PBXInAFlash appears to be the easiest and quickest answer to adopt.
FreePBX
Incorporating the very best of both worlds, and trying to control the fantastic work probably created by the Asterisk task, FreePBX is actually a web based, open source graphical user interface (GUI) to assist owners better manage as well as configure their Asterisk based method. Even though the project uses the Asterisk process, users are able to obtain often simply the GUI to add on to their current system, or maybe the whole package which includes a pre configured method OS, Asterisk, and the FreePBX GUI on top and all the required dependencies. Therefore while adopting simply Asterisk might require some much more specialized expertise in order to take full advantage of, or even to create the own GUI of yours, FreePBX brings all the ingredients.
FreePBX additionally can help you create your limitless SIP Trunks because of SIPSTation integration straight into the platform. FreePBX additionally comes with an extended list of business modules as well as add ons to improve the program of yours with a lot more features, along with a reseller plan to ensure proper education, quality, and balance to end users and resellers. Basically, the system is going to train as well as educate your support and product sales staff in case you’re trying to repackage and promote the item of yours.
There are some different VOIP needs like Proxy, dispatcher and some of the load balancing features, for such case there are different open source solutions as mentioned below the best and frquently used.
OpenSIPs
With a stronger focus on open source implementation of a SIP server, OpenSIPs still can help you create your impartial, custom Unified Communications program and a PBX. The platform supports voice, video, IM as well as presence products with a modular and scalable style, hence similar to some other platform, it must be as customizable as you want it to be. OpenSIPs is actually labeled as one of probably the fastest SIP servers as well as comes with a strong option at an enterprise or maybe carrier grade category.
OpenSIPs actually offers a continuing list of benchmarks as well as performance testing to back up the claim of theirs. In a similar manner to Asterisk, OpenSIPs gives captured webinars as well as in depth manuals for each edition as well as setup of the OpenSIPs platform. A web based setup portal should allow it to be easy to collect statistics and information of the service of yours, and also on the fly configurations.
Kamailio
With fifteen years of development under the belt of theirs, Kamailio goes on to create on and grow the open source SIP server of its. With effective capabilities like asynchronous TCP, SCTP and UDP, TLS to confirm protected communications for the VoIP information of yours like speech video as well as text, and also WebRTC support the effort shows. Kamailio additionally supports instant messaging as well as presence, together with much more behind the scenes features including least price routing, load balancing, routing fail over as well as authorization and authentication for enhanced security.
Kamailio provides one of probably the strongest amount of protection we have observed on this list and could be a good recommendation for just about any team or maybe small business which has to make almost everything as locked down and secure as possible because of the degree of encryption the platform offers. On the other hand, Kamailio may be a bit much more tough to adopt, needing a lot more in depth information of the SIP protocol itself to completely control the platform.