# PBX
> Private Branch Exchange – a private telephone network used within an organization

A PBX (Private Branch Exchange) is a private phone system that routes calls within an organization.

## What is a PBX?
A Private Branch Exchange (PBX) is a private telephone system used within an organization to manage internal and external calls. It handles call routing, extensions, voicemail, conferencing, and other telephony features without requiring a separate phone line for every user.

## Evolution of PBX
Traditional PBX systems were hardware-based and connected to the PSTN via analog or ISDN lines. Modern deployments have evolved to [IP PBX](/voip-glossary/ip-pbx/) (using VoIP) and [Cloud PBX](/voip-glossary/cloud-pbx/) (fully hosted), dramatically reducing cost and complexity.

## Related Terms
- [IP PBX](/voip-glossary/ip-pbx/)
- [Cloud PBX](/voip-glossary/cloud-pbx/)