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ISDN Primary Rate Access

ISDN Primary Rate Access product (eg Telstra OnRamp30) gives 30 x B channels, at 64kbps each and an additional 64 kbps D (or signalling) channel, conceptually:
ISDN Primary-rate interface
The number of B channels can be increased in multiples of 10.

The NT2 (typically a PABX) connects to a special OnRamp NT1, at a point called the T interface. An S interface can be provided on the customer side of the NT2.
 
Note that in the USA and Japan, the primary rate service is instead 20B+D over a 1.544 Mbps (called a T1) bearer.
 
Where all of the available B channels are dedicated as a "leased line" point-to-point data service, users refer to an E1 (2Mbps) or T1 connection speed.
 

Lecture 15: Internet Topology and Structure Copyright © 2004 P.Scott, La Trobe University Bendigo.



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