What is the Difference Between PRI and T1 Service?

The term PRI refers to Primary Rate Interface. This is a service provided by the ISDN, or Integrated Services Digital Network. ISDN provides two basic levels of service. The first, and most common, is known as BRI, or Basic Rate Interface. The second is known as PRI, or Primary Rate Interface. Both of these services are a method in which many voice and data transmissions can be sent and received over a single fiber-optic cable.