ISDN PRI (North America)

ISDN PRI (North America)
In North America, ISDN PRIs are provisioned over T-1 standards. The T-1 standard, also called
DS1, is capable of servicing 24 64Kbps channels—each channel being historically provisioned
for a single voice connection. From this, 23 B channels are allocated, with the last 64Kbps channel
used for D channel signaling.
The most important thing to note, in addition to the channels of ISDN PRI, is that ISDN PRI
operates over channelized T-1 connections. This means that at its core, each B channel is one
time slot in the T-1 specification, although clearly, there is additional functionality. PRI requires
only two pairs of copper wire (the same as T-1); however, all installations should use RJ-45,
which has four pairs. This provides a visual variance to RJ-11 ports, and typically RJ-45 provides
a better, cleaner connection.