PBX is a business telephone system generally used to describe multiple call management features like outbound and inbound lines, voicemails, and call routings etc. It generally stands for Private Branch eXchange. PBX is based on a hardware system which is required to handle the call routings and call switching between a specified business location and adjacent telephonic network. It can be very easily understood by a simplified analogy of switchboard operator used for switching and routing. The name, Public Branch eXchange has originated from its functional operation, the way it interacts with PSTN networks. While the term 'Private' separates it out from PSTN that it is different from Public Switched Telephone Network (PSTN), regardless of the fact that it can also be connected to it.