If you have ever dialled a three-digit extension to reach a colleague, you have used a PBX. Yet the terms around it, PBX, PABX, EPABX, IP PBX and cloud PBX, confuse many buyers. This guide explains what a PBX system is, the full forms, the types available in India and how a modern PBX works.
What is a PBX?
A PBX is a private telephone exchange that belongs to one organisation. It connects the phones inside an office to each other, so staff call colleagues by extension number for free, and connects them to the outside world through a limited number of phone lines. Instead of giving every desk its own line, the PBX shares lines across everyone.
PBX, PABX and EPABX: full forms
| Term | Full form | Meaning today |
|---|---|---|
| PBX | Private Branch Exchange | The general name for a business phone system |
| PABX | Private Automatic Branch Exchange | A PBX that connects calls automatically, without an operator |
| EPABX | Electronic Private Automatic Branch Exchange | The common Indian name for an electronic office PBX, usually analog or digital hardware |
| IP PBX | Internet Protocol PBX | A PBX that runs calls over your computer network |
| Cloud PBX | Hosted PBX | A PBX run by a provider in a data centre, rented as a service |
In India, “EPABX” and “intercom” are often used for any office phone system. Today most new installations are IP PBX systems.
What does a PBX do?
- Extensions: every desk, room or user gets a short number.
- Internal calls: free calls between extensions.
- Shared lines: many extensions share a few outside lines or a SIP trunk.
- Call transfer, hold and pickup: move calls between people.
- Reception and IVR: greet callers and route them by menu.
- Call control: decide who can call where. See call restrictions.
- Voicemail, recording and reports on modern systems.
Types of PBX systems
Analog and digital EPABX
Hardware boxes with cards for lines and extensions, wired to analog or digital phones. Reliable, but expanding means adding cards and cabling, and features are limited.
IP PBX
Runs on a server or appliance on your network. Phones connect over the LAN, so adding a user means adding an extension, not new wiring. IP PBX systems add IVR, voicemail to email, recording, softphones, mobile apps and reports. They can still connect old analog phones through gateways. Compare them in EPABX vs IP PBX.
Hybrid PBX
An IP PBX that also connects analog phones, PRI lines or analog lines, useful while moving from old to new.
Cloud PBX
The provider hosts the PBX; you pay monthly per user. Read cloud vs on-premise PBX to choose.
How a modern IP PBX works
- Phones register to the PBX: IP desk phones, softphones on laptops, mobile apps, or analog phones through a gateway.
- Lines connect the PBX to the telecom network: SIP trunks, PRI E1 lines or analog lines.
- Incoming calls follow rules: by number, by time of day, through an IVR, to a ring group or queue.
- Outgoing calls follow outbound routes that pick the line and check each user’s permissions.
- Everything is logged for reports and, where enabled, recorded.
Which PBX is right for you?
- Small office, a few lines: a small IP PBX, or a cloud PBX if you have no server room.
- Growing business or multiple floors: an on-premise IP PBX with IP phones and SIP trunks.
- Hospitals, factories, schools, government: an on-premise IP PBX with paging, call restrictions and TEC certification. See TEC certified IP PBX.
Voxdial IP PBX by BitVoice is a PBX system made in India, TEC certified under MTCTE. See PBX system price in India or book a demo.
FAQs
What is the full form of PBX?
PBX stands for Private Branch Exchange, a private telephone exchange that serves one organisation.
What is the full form of EPABX?
EPABX stands for Electronic Private Automatic Branch Exchange. In India it is the common name for an office telephone or intercom system.
What is the difference between PBX and IP PBX?
A traditional PBX connects phones over dedicated telephone wiring. An IP PBX connects phones over your computer network and adds features such as IVR, voicemail to email, softphones and call recording.
What are the types of PBX systems?
Analog and digital EPABX, IP PBX, hybrid PBX that mixes IP and analog, and cloud or hosted PBX.
