PBX — Private Branch Exchange
What is PBX?
A PBX (Private Branch Exchange) is the phone system that manages call routing, extensions, voicemail, and features like call forwarding and ring groups within a single business, connecting internal extensions to each other and to the outside line via a trunk. A traditional PBX was on-premises hardware; a cloud (hosted) PBX runs the same call-control logic as a hosted service delivered over the internet, connecting to carriers via SIP trunking instead of physical phone lines.
More detail
A cloud PBX shifts the hardware, maintenance, and upgrade burden to the hosting provider, while still giving a business its own dial plan, extensions, ring groups, and call routing rules.
Internal calls between extensions on the same PBX typically never touch the outside trunk at all — only calls to or from an external number cross the SIP trunk to the carrier.
Frequently asked
- What's the difference between a traditional PBX and a cloud PBX?
- A traditional PBX is physical hardware installed on-site that a business maintains itself; a cloud PBX delivers the same call-routing, extension, and voicemail functionality as a hosted service over the internet, typically billed as a subscription with no on-site hardware to maintain.
- Does every call go through the PBX?
- Every call routed within the business's phone system does — including purely internal extension-to-extension calls, which a PBX typically handles without ever touching the outside SIP trunk or carrier network.
See also
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