Asterisk
Easy to use but advanced IP PBX system, VoIP gateway and conference server.
ASTPP
VoIP Billing Solution for Freeswitch. It supports prepaid and postpaid billing with call rating and credit control. It also provides many other features.
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.
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.
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.
Freepbx
Web-based open source GUI that controls and manages Asterisk.
FreeSWITCH
Scalable open source cross-platform telephony platform.
Kamailio
Modular SIP server (registrar/proxy/router/etc).
openSIPS
OpenSIPS is an Open Source SIP proxy/server for voice, video, IM, presence and any other SIP extensions.
Routr
A lightweight sip proxy, location server, and registrar for a reliable and scalable SIP infrastructure.
SIP3
VoIP troubleshooting and monitoring platform.
SIPCAPTURE Homer
Troubleshooting and monitoring VoIP calls.
Wazo
Full-featured IPBX solution built atop Asterisk with integrated Web administration interface and REST-ful API.
Yeti-Switch
Transit class4 softswitch(SBC) with integrated billing and routing engine and REST API.