While ISDN BRI is
highly common in Europe, its usage in USA is very rare.
ISDN Primary Rate Interface (PRI)
ISDN PRI connections are separated into two type??”E1 and T1. While E1 circuits are
mainly used in Europe, Africa, and Asia, the T1 interface is mainly used in North
America and Japan. The differences between the two are as follows:
ISDN
Type
D-Channels B-Channels Aggregate Throughput
E1 PRI 1 (normally
channel 24)
30 30 * 64kbps = 1920kbps + 16kbps = 1936kbps
T1 PRI 1 (normally
channel 16)
23 23 * 64kbps = 1472kbps + 16kbps = 1488kbps
In many situations, an E1 PRI circuit will be referred to as a 2Mbps circuit, while a T1
circuit will be referred to as a 1.5Mbps circuit. While a PRI is much larger than a BRI
interface, in terms of size, both utilize the same signalling operational methodologies,
and also enjoy a similar feature set.
To learn more about the ISDN protocol, visit the ISDN information page
on Wikipedia, which has a multitude of information and is fairly accurate
for the novice user. ISDN on Wikipedia: http://en.wikipedia.org/
wiki/Integrated_Services_Digital_Network.
An Introduction to Telephony and Asterisk
[ 12 ]
Foreign Exchange Office (FXO) and Foreign Exchange
Station (FXS)
These two interfaces tend to confuse many people, and the confusion is very much
understandable.
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