Short for Primary-Rate Interface,
a type of ISDN
service designed for larger organizations. PRI includes 23 B-channels
(30 in Europe) and one D-Channel. In contrast, BRI (Basic-Rate Interface)
, which is designed for individuals and small businesses, contains just two B-channels and one D-channel.
PRI service is generally transmitted through a T-1 line (or an E1 line in Europe).