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. |