EPABX Intercom System Guide: Lines, Extensions and Choosing the Right Model
An EPABX (Electronic Private Automatic Branch Exchange) connects your incoming telephone lines to many internal phones and lets everyone call each other free over intercom. Offices, factories, hotels, hospitals, schools and large homes use them.
Lines vs extensions
- CO lines (main lines) – the outside telephone lines from your service provider.
- Extensions – the internal phones (reception, cabins, rooms, gate).
An EPABX is usually described as lines × extensions, for example 2 × 8 means two outside lines shared by eight internal phones.
Reading common model numbers
Many popular EPABX models follow a pattern where the first digit is the number of CO lines and the rest is the number of extensions:
| Model | Lines | Extensions | Typical use |
|---|---|---|---|
| 104 | 1 | 4 | Homes, small shops |
| 108 | 1 | 8 | Small offices, clinics |
| 206 | 2 | 6 | Offices with two numbers |
| 308 | 3 | 8 | Growing offices |
| 416 | 4 | 16 | Medium offices, schools |
| 424 | 4 | 24 | Factories, hotels, hospitals |
Always confirm the exact line and extension count on the product page, as some brands vary.
How to size your system
- Count every place that needs a phone, including the gate and store room — that is your extension count.
- Count your outside numbers today and next year — that is your line count.
- Leave 2–4 spare extensions for growth.
Useful features
- Caller ID (CLI) shows who is calling on the extension phones.
- Door lock / door phone integration lets you talk to the gate and open an electronic lock from any extension.
- Call barring controls which extensions can make outside or mobile calls.
- Background music and day/night modes on many models.
Pax intercoms (no outside lines)
If you only need internal calling — between floors, rooms or buildings — a PAX intercom is simpler and economical.
Frequently asked questions
Can I use any landline phone as an extension?
Most EPABX systems work with standard corded landline phones. Combos with matched phones are the easiest option.
Do you supply complete kits with phones?
Yes, we have EPABX combos with phones from leading brands. For large projects, get a bulk quote.
