Telos TWOx12 - Ordering ISDN - an Introduction

TELOS TWOX12 USER’S MANUAL
INSTALLATION
CHAPTER 2 14
TA
ISDN EQUIPMENT
NT1
To
Telco
U
Interface
reference
point
S/T
Interface
reference
point
ISDN network connection reference points.
In the USA & Canada the NT1 is owned by the end-user whereas in the rest of
the world it belongs to the Telecom Agency.
Only one NT1 may be connected to a U interface. However, as many as eight terminals
may be paralleled onto the S bus.
The North American version of the TWOx12’s ISDN interface has 2 internal NT1s per
interface card with the U interface connectors available at the rear panel.
Section 2.5 has specific information on connecting the unit in various regions of the
world.
2.4 Ordering ISDN – an introduction
This section has a quick overview, for specific information on ordering ISDN see Appendix
6 (Euro ISDN) and Appendix 7 (USA & Canada). The Telos TWOx12 supports the usual
protocol standards:
For USA & Canada
• National ISDN 1 & 2 (these are the preferred options)
• AT&T “Custom Point-to-Point” (may only allow a single channel)
• Northern Telecom (Nortel) DMS-100 “Custom functional”
For Europe and many other parts of the world
• “Euro ISDN” according to ETS-300 (NET-3, ISDN-2, BRI, S∅)
B and D Channels
The B “Bearer” Channels are the 64 kbps paths that carry the voice audio. The D “Data”
channel is the path between the central office and terminal equipment that is used for call
set-up and status communication. All lines must have a D channel, but there is sometimes a
choice as to the number of enabled B channels.