sip

Freepbx - Web-based open source GUI that controls and manages Asterisk. GPL-2.0 PHP

Asterisk - Easy to use but advanced IP PBX system, VoIP gateway and conference server. GPL-2.0 C/deb

Flexisip - A complete, modular and scalable SIP server, includes a push gateway, to deliver SIP incoming calls or text messages on mobile device platforms where push notifications are required to receive information when the app is not active in the foreground. AGPL-3.0 C/Docker

Kamailio - Modular SIP server (registrar/proxy/router/etc). GPL-2.0 C/deb

openSIPS - OpenSIPS is an Open Source SIP proxy/server for voice, video, IM, presence and any other SIP extensions. GPL-2.0 C

FusionPBX - Open source project that provides a customizable and flexible web interface to the very powerful and highly scalable multi-platform voice switch called FreeSWITCH. MPL-1.1 PHP

FreeSWITCH - Scalable open source cross-platform telephony platform. MPL-2.0 C

ASTPP - VoIP Billing Solution for Freeswitch. It supports prepaid and postpaid billing with call rating and credit control. It also provides many other features. AGPL-3.0 PHP

Eqivo - Eqivo implements an API layer on top of FreeSWITCH facilitating integration between web applications and voice/video-enabled endpoints such as traditional phone lines (PSTN), VoIP phones, webRTC clients etc. MIT Docker/PHP

Routr - A lightweight sip proxy, location server, and registrar for a reliable and scalable SIP infrastructure. MIT Docker/K8S

SIP3 - VoIP troubleshooting and monitoring platform. Apache-2.0 Java

SIPCAPTURE Homer - Troubleshooting and monitoring VoIP calls. AGPL-3.0 Nodejs/Go/Docker

Wazo - Full-featured IPBX solution built atop Asterisk with integrated Web administration interface and REST-ful API. GPL-3.0 Python

Yeti-Switch - Transit class4 softswitch(SBC) with integrated billing and routing engine and REST API. GPL-2.0 C++/Ruby