PBX overview
What is a PBX?
The term PBX stands for Private Branch Extension. You probably refer to your PBX as a phone system.
Your PBX incorporates your telephones, fax machines, modems, and more known as extensions. Your PBX handles calls between these extensions as well as connections to the PSTN via trunk lines.
Your PBX was originally devised by telecommunications companies as a way to make internal communications more efficient. In the early days of telecommunications any call you made - internal or external - needed to be routed through your telecommunication provider’s central office.
This was done primarily for cost savings purposes.
Over the years your PBX has advanced to the point of offering services that were not available from your telecommunications provider, such as hunt groups, call forwarding, and extension dialing.
Note that PBX systems are different from key systems. A Key system allows uses to manually select their own outgoing lines while a PBX system selects an outgoing line automatically.
The PBX is changing
During the 1990’s three trends emerged that changed the nature of PBX systems.
- There was massive growth in the use of data networks
- Public understanding of packet switching increased
- The growth of the Internet
Since companies were already using packet switched networks for data, understood how the technology worked and the Internet became a globally delivery system sending telephone calls in this manner seemed like a logical next step.
These factors led to the development of the VoIP PBX which you will learn more about here. (Technically, nothing was being “exchanged” anymore, but the acronym PBX was so widely understood that it remained in use.)