The Taridium ipbx is a complete software-based VoIP PBX system that replaces a traditional proprietary hardware PBX. It runs on Linux without the need for extra software licenses, and is based on the SIP standard. It supports many phones and is available for free in a 5 user version.
sYnergy is a Web-based groupware and communication solution for use with an intranet. It includes email mailboxes, a fax viewer and sending function, contact lists, an appointment and task management function, a picture database, and a function for listening to voice messages. The extensive user management enables administrators to assign various permissions to each user and to exchange data e.g. contacts, appointments, or tasks. It also offers a function to import existing data.
YaaCs (Yet Another Advanced Cati system) is written in Tcl/Tk to manage and realize computer assisted telephone interviewing (CATI) and telemarketing. It make easy monitoring survey progress (giving several information), and it allows the management of the the survey with several administration tools. It simplifies the interviewer's work reading all contact's data from an easy and functional GUI. It can send faxes via hylaFAX and save all contact's data in a PostgreSQL database.
CapiSuite is an ISDN telecommunication suite providing easy-to-use telecommunication functions which can be controlled from Python scripts. It uses a CAPI-compatible driver for accessing the ISDN-hardware, so you'll need a CAPI-compatible driver. CapiSuite is distributed with two example scripts for call incoming handling and fax sending. They provide a multi-user answering machine with fax recognition, remote inquiry, and fax receiving/sending functions.
Callweaver is a community driven software PBX project. The most important differences between Callweaver and Asterisk are built-in STUN support, the use of SpanDSP for better codecs and full T.38 fax over IP support, Sqlite instead of Berkeley DB, universal jitterbuffer, POSIX timers to avoid Zaptel timing dependencies, greater speed, more efficient dialplan execution, and greater stability.
Sipcat is a software IP telephony system that helps businesses increase productivity and reduce telecommunication costs. It allows you to start running your own voice over IP PBX in a matter of minutes. It contains a complete Linux distribution, including Asterisk and all required 3rd party software.
VOCP is a complete messaging solution for voice modems, with voicemail, fax, email pager, DTMF command shell and Text-to-Speech support, 4 graphical interfaces, and a Web interface. Callers navigate the system using a touch-tone phone and may send and receive faxes, voice mail, and pager messages, listen to text/HTML email messages, or execute configured programs on the host and hear the resulting output.