Primary Rate Interface (PRI)

What is PRI?

Primary rate interface (PRI) is a telecommunications interface used in an Integrated Services Digital Network (ISDN).

PRI phone systems operate via on-premise connections to the Public Switched Telephone Network (PSTN) to send voice and data signals across telephone lines.

A PRI is a form of Time Division Multiplexing (TDM), allowing you to send up to 23 separate communications via voice, data, or video. Channels are typically used by larger enterprise companies with a PBX system to help with access to the PSTN.


PRI phone systems are the traditional choice for voice services. SIP (Session Initiation Protocol) trunking, on the other hand, is cloud-based.

Compared to PRI, SIP trunking gives businesses greater flexibility, scalability, and cost-effectiveness. Learn more about PRI vs. SIP.

How Bandwidth is involved with PRI?

With technology advancing, companies are actively replacing PRI circuits with a more scalable SIP-based infrastructure. Bandwidth provides SIP services so our customers can deliver quality communication services.

Many SIP Trunking providers are merely resellers, relying on several other carrier’s networks. When you call these help desks, all they can do is open a ticket with their carriers and wait. When you call Bandwidth, you’re talking directly to the people who can solve your problem.

Bandwidth owns and operates one of the nation’s largest and fastest-growing All-IP Voice Networks. We’re the SIP provider you can count on to deliver quality, affordability, scalability, and exceptional service.

This post was last updated on Feb. 22, 2024.