Asterisk is the number one open-source telephony software solution that is developed by Digium. As the asterisk is a telephony solution thus it can interface with telephone systems as well as with a few modern ones like skype and the addon skype for asterisk. By using interface cards, the asterisk is able to communicate with the public telephone network and analog phones thus it possesses both kinds of functionality. Moreover, it can also be used to communicate with common VoIP systems as it is highly versatile in nature. Asterisk powers IP PBX systems, VoIP gateways, conference servers, and it is also used by SMBs, enterprises, call centers, carriers, and governments worldwide.
Asterisk is widely and commonly used as a fully-featured private branch exchange (PBX). Additionally, it allows the calls to be switched between enterprise users on their local lines while allowing all the users to share a set of numbers of external phone lines. PBX is allowing the help to save companies money by not requiring a line for each user to that company's head office. A big thanks to the large community of users as new features are continuously added, all the issues are resolved and all bugs are fixed without any delay.