What a PBX does
Instead of giving every employee a separate outside line, a PBX gives each person an internal extension and manages how calls enter and leave the organization. It is the switchboard behind your business phone number.
- Routes inbound calls to the right extension, group, or queue
- Connects extensions to each other without using outside lines
- Manages outbound calling through one or more carriers or trunks
- Provides voicemail, call transfer, hold, conferencing, and an automated attendant
- Applies rules based on time of day, caller, or dialed number
The main types of PBX
- Traditional PBX: an on-site hardware cabinet connected to analog or digital phone lines. Reliable but expensive to expand and maintain.
- IP PBX: software running on a local server that uses VoIP internally and connects to the outside world through SIP trunks or gateways.
- Hosted or cloud PBX: the same functionality delivered from the provider's cloud, with no switch to maintain on site.
How a call flows through a PBX
An inbound call arrives from the carrier and reaches the PBX. The PBX checks its rules: it may play a greeting through an auto attendant, ask the caller to choose an option, then ring an extension, a ring group, or a queue. If no one answers, the call goes to voicemail. For outbound calls, the PBX applies dialing rules, picks a trunk or carrier, and connects the call.
Why businesses are moving off on-premises PBX
On-site systems require capital expense, specialist maintenance, and extra work to support remote employees or new offices. Cloud systems scale by adding users, work from anywhere with an internet connection, and receive feature updates without hardware changes. Many organizations migrate when a system reaches end of life or when they open a second location.
Common questions
- What does PBX stand for?
- PBX stands for Private Branch Exchange.
- What is the difference between a PBX and VoIP?
- A PBX is the system that manages a company's calls. VoIP is the technology that carries voice over IP networks. Modern PBX systems use VoIP to place and receive calls.
- What is the difference between PBX and PABX?
- PABX stands for Private Automatic Branch Exchange. Today the terms are used interchangeably, because virtually all modern exchanges are automatic.
- Do I still need desk phones with a PBX?
- Not necessarily. Many businesses use softphone apps on computers and mobile devices, IP desk phones, or a mix of both.