Nortel Networks Circuit Card 311 - Manual (Page 1004)

1004 NTCK16 Generic Central Office Trunk cards
Loop start operation
Loop start operation is configured in software and is implemented in the
card through software download messages.
Idle state
In the idle state, the ringing detector is connected across the tip and ring
wires, providing a high impedance loop toward the Central Office.
Call placed by Central Office
The Central Office initiates a call by applying ringing between the tip and
ring wires. If the call is answered, the ringing detector on the trunk card
is switched out and a low resistance dc loop is placed between the tip
and ring leads.
On trunks configured for battery supervision, the battery detector records
the polarity of the tip and ring wires and sends an answer acknowledge
signal to software.
Call placed by CS 1000E, CS 1000M, and Meridian 1
To initiate a call, the CS 1000E, CS 1000M, and Meridian 1 switches out the
ringing detector and places a low resistance loop across the tip and ring
leads. On trunks configured for battery supervision, the trunk card sends a
seize acknowledge signal to software.
The system sends digits in the form of Dual Tone Multifrequency (DTMF)
tones or pulse digits. When the far-end answers, the Central Office reverses
polarity. If the trunk is configured for battery supervision, it sends a polarity
reversal message to software.
Central Office disconnect
There are two ways the Central Office can disconnect the call:
• by applying busy tone toward the CS 1000E, CS 1000M, and Meridian 1.
If the trunk card is configured to detect busy tone, it sends a disconnect
message to software.
• by reversing battery. If the trunk card is configured to detect battery
reversal, it sends a disconnect message to software. When the unit on
the trunk card is idled, the trunk card sends a release confirm message
to software.
CS 1000E, CS 1000M, and Meridian 1 disconnect
The CS 1000E, CS 1000M, and Meridian 1 disconnects the call by removing
the loop between the tip and ring leads and replacing the ringing detector.
Trunks configured for battery supervision send a release confirm message
to software.
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 01.04 Standard
Release 5.0 23 May 2008
Copyright © 2003-2008, Nortel Networks
.