SIP, Session Internet Protocol, is a signal protocol meant to create, modify or terminate sessions with one or more applicants. These sessions are mainly Internet telephone calls, multimedia distribution, and multimedia conferences. SIP was accepted as a 3GPP signaling protocol and permanent element of the IMS architecture in November 2000. SIP is widely used as a signaling protocol for Voice over IP, with H.323 and others.

Private Branch Exchange, switches calls between VoIP users on local lines, while allowing all users to share a certain number of external phone lines.

What draws many people to make the switch from their normal phone system to Asterisk? What are the benefits and the upsides of using Asterisk? Will it save you additional costs?