U.S. ISDN Primary Rate Interface (PRI) Lines

This table shows the number of ISDN PRI lines installed by the U.S. RBOCs. The long distance carriers such as AT&T, MCI, and Sprint probably have an equal number of ISDN PRI lines installed. This chart shows only the AT&T ILEC BRIs and not its AT&T long distance BRIs. Corrections have been made to rationalize the numbers from the FCC ARMIS database.

ISDN PRI has become a popular way to provide trunking services to PBX systems and is just now starting to be supplanted by VoIP network connections. ISDN PRI is also a popular way for terminating dialup networks. The movement from dialup to broadband connections has reduced the demand for PRI and is probably the primary reason for the decline we have seen recently.

ISDN PRIs have resumed a slow rate of growth. The disconnections due to the dramatic shift from dial up Internet access to broadband seems to have run its course.