Asterisk is an open source and free software implementation of a telephone PBX VoIP solution. Asterisk offers features such as:
=> Voice-over-Internet protocol (VoIP)
=> Voice mail
=> Conference calling
=> Interactive voice response i.e. phone menus
=> Automatic call distribution
=> Custom programming in C or Perl using AGI
From the article:
Voice over Internet Protocol (VoIP) has emerged as a popular technology for modern voice communications. Many organizations have replaced their analog or proprietary digital telephone systems with VoIP-based solutions. This allows the consolidation of telephone services into an existing IP infrastructure. In addition, using IP to host voice services lets the organization leverage existing expertise–while retaining all of the network’s management advantages. Though not without its disadvantages, VoIP provides a compelling option to those looking for a telephone solution.
This article will present a simple VoIP solution using Asterisk, an open source private branch exchange (PBX) product. It will show you how to install Asterisk, configure it using its LDAP backend, and connect to it using the Ekiga software VoIP client and a Cisco 7900 Series VoIP telephone to make calls.