Asterisk is a complete PBX in software.  It provides all of the
features you would expect from a PBX and more. Asterisk does voice
over IP in three protocols, and can interoperate with almost all
standards-based telephony equipment using relatively inexpensive
hardware.

Asterisk provides Voicemail services with Directory, Call Conferencing,
Interactive Voice Response, Call Queuing. It has support for
three-way calling, caller ID services, ADSI, SIP and H.323 (as both
client and gateway).

This is an EOL long term support version.  It went to security fixes
only on 2020-10-24, and EOL on 2021-10-24. For more information about
Asterisk versions, see
https://docs.asterisk.org/About-the-Project/Asterisk-Versions/

NOTE:  This version does not work with the zaptel drivers.  It
requires the newer DAHDI drivers which are still being ported.
So, there is no hardware support available at this moment.

Homepage:
https://www.asterisk.org/
