The primary rate interface is an ISDN service delivered over T1 (in North America) or E1 (in Europe) lines. A T1 PRI provides 23 bearer channels and one data channel (23B+1D) for signaling, allowing a business to handle 23 simultaneous external calls. It connects enterprise PBX systems directly to the public switched telephone network with digital clarity and rapid call setup.
The customer is complaining about busy signals, so check if all 23 channels on their PRI are maxed out.
Related terms
Primary rate interface
An enterprise-grade ISDN connection that bundles multiple digital voice and data channels over a single physical line.
ISDN
Integrated Services Digital Network is an older standard for transmitting digital voice and data over standard telephone lines.
PBX
A private telephone network used within a company or organization.
T-carrier
A North American standard for digitally multiplexing voice and data signals.