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.
Ding is a PHP framework that provides dependency injection (by Setter, Constructor, and Method), Aspect Oriented Programming, XML, YAML, Events support, and some JSR 250/330 annotations as bean definition providers, lightweight, can be deployed as a PHAR file, simple, and quick MVC, syslog, TCP client and server with non-blocking sockets, timers, and custom error, signal, and exception handling, PAGI integration (for the Asterisk gateway interface), and PAMI integration (for Asterisk management). It is similar to Java's Seasar and Spring.
Shift8 provides a simple mechanism for using the AJAM Asterisk interface in PHP. Apart from the obvious reason of providing an easy way to talk with a remote Asterisk server, the main benefit of having an intermediate library between your software and an Asterisk server is mostly that you can isolate the remote Asterisk, protecting the credentials and the entire PBX.
phpivr is an Asterisk AGI application which uses PHPAGI to organize Interactive Voice Responses. It doesn't need extensions.conf changes and dialplan reloading if you want to modify the IVR menu, it reads phpivr.conf on the fly. It supports unlimited levels of IVR menus. It is a standalone tool (you do not need to install FreePBX with all its functionality), does not require additional exotic libraries, and is easy to integrate into your own application.
GROUP-E is collaboration software which integrates groupware, project management, and business server on one platform. The solution is based on a LAMP architecture (Linux, Apache, MySQL, PHP). GROUP-E offers project management, transparent Samba (file server) integration, integration of Cyrus IMAP server with administration and personal SIEVE filters, support for SyncML 1.0, LDAP-based user management with single sign-on authentication, and LDAP contact databases. GROUP-E also provides ActiveSync for synchronization.
Elastix is a software appliance that integrates the best tools available for Asterisk-based PBXs into a single, easy-to-use interface. It also adds its own set of utilities and allows for the creation of third party modules. The goals of Elastix are reliability, modularity, and ease-of-use. It also features strong reporting capabilities.
VoiceOne is a Linux distribution that gives you the ability to install a PBX platform with an easy to use Web-based GUI. It also provides a framework for building a communication server adding various plugins. Its main features are Asterisk 1.8 with realtime configuration with MySQL, a Ubuntu 10.04 base, and support for both hard disk and Compact Flash card installation.
LDAP Account Manager (LAM) is a web frontend for managing entries (e.g. users, groups, DHCP settings) stored in an LDAP directory. LAM was designed to make LDAP management as easy as possible for the user. It abstracts from the technical details of LDAP and allows persons without technical background to manage LDAP entries. If needed, power users may still directly edit LDAP entries via the integrated LDAP browser.