Asterisk is a telephone exchange (PABX) in free software,
multi-platform (Linux, BSD and MacOSX), published under licence LPG.
The supported protocols are SIP, H323 and IAX (Inter-Asterisk
eXchange). This power station provides in particular the following
services: voice messaging, conference, vocal waiter, distribution of
the calls, reception of fax. A footbridge towards the standard public
networks (traditional telephony (STN), mobile telephony (GSM), etc.)
is also provided. The instigator of the project is Mark Spencer of the
Digium company.