Asterisk Hardware

Asterisk is a free software / open-source software implementation of a telephone private branch exchange (PBX). Like any PBX, it allows a number of attached telephones to make calls to one another, and to connect to other telephone services including the PSTN. "Its name comes from the asterisk symbol, *, which in Unix (including Linux) and DOS environments represents a wildcard, matching any filename."
Asterisk Hardware