VoIP glossary · Primary Rate Interface
What is PRI?
A PRI (Primary Rate Interface) is a digital phone line that carries 23 voice channels in North America (T1) or 30 channels in Europe and most other regions (E1) over a dedicated circuit.
PRI explained
For decades PRI was how medium and large businesses connected their phone systems. It is reliable but inflexible: capacity comes in fixed blocks, installation takes weeks, and the line is tied to one building. Many incumbent carriers are now retiring their PRI and ISDN services.
A SIP trunk does the same job over an internet connection, with channels added in single units and numbers that can move between sites. Older PBXs with only PRI ports can still use SIP trunks through a gateway.
Example
An office with one E1 PRI (30 channels) moves to a SIP trunk with 20 channels, matching its real peak usage and keeping its existing numbers.
Put it into practice
Prepaid SIP trunks and wholesale routes from $200. Ask sales for rates or the NOC for a technical answer.