Asterisk is an open source software use as a telephone private branch exchange (PBX).

Asterisk allows attached telephones to make calls to one another, and to connect to other telephone services including the public switched telephone network (PSTN).Asterisk get its name from the asterisk symbol, “*” mean everything in computing world.

Asterisk support all the standard features of a telco like sending and receiving caller ID and allow us to route calls on the basis of Caller ID. Its also support the features likes:

Call waiting

Call forwarding

Transferring call.