PRI stands for Primary Rate Interface. It is part of the ISDN or Integrated Services Digital Network specification. ISDN was envisioned as a way for all telephone lines to move from analog to digital. The basic service is called BRI or Basic Rate Interface. It offers two phone lines, a phone line and a 64 Kbps data service or a 128 Kbps data service. ISDN BRI never took off to become the popular small business and residential service that was intended. What happened is that DSL and Cable broadband emerged to deliver much higher bandwidths. Telephone service has made a major transition to cell phones and VoIP. Even so, BRI is still popular, where available, for radio station remote broadcasts & interviews.
ISDN PRI, the big brother to BRI, is now the most popular way to connect to a PBX telephone system for businesses and other organizations. As a digital phone service it is configured into 23 separate digital telephone lines plus a data channel for switching and Caller ID.
PRI service is available just about everywhere. That’s because it was designed to ride on a common 24 channel T1 line provisioned on two twisted pair copper wires. Nearly all businesses have bundled twisted pair cables already installed for multi-line telephone service. A couple of extra pairs can easily be put to use to bring in ISDN PRI, also called T1 PRI.
When businesses get to a size where they need 10 or 12 outside phone lines, it generally makes sense to replace all those separate lines with a single ISDN PRI digital trunk. You don’t need to run a PRI at full capacity. You can save money over analog service by using only half the 23 line capacity.
Most call centers can easily use 23 phone lines. So what do you do when you run out of capacity? That’s easy. Just install a second PRI line and get 23 additional outside lines. The PBX phone equipment used to manage those lines for the agents comes with ISDN PRI connectivity already built-in or easily added with a circuit card. Many circuit cards can handle up to 4 PRI lines for a total of 92 outside lines. Larger systems can handle multiple interface cards.
How can those lines be configured? That’s up to you. The lines can be set up to handle any combination of local, long distance, incoming only, outgoing only, incoming & outgoing calls, toll free numbers, and DID or Direct Inward Dialing that gives every phone its own unique number.
The competition to ISDN PRI lines is SIP trunking. Both types of line services will work with either conventional PBX or the newer IP PBX telephone systems. Which is optimum for the call center connectivity you need? Get customized pricing and availability of digital phone line service for your business location so you can make the best decision.
