Nortel Circuit Card, Installation Manual, Page: 602 / 908

Page 602 of 906 NT8D14 Universal Trunk card
553-3001-211 Standard 3.00 August 2005
Figure 137
Two-way, loop OAID, TIE trunk call connection sequence – outgoing call to far-end PBX
A
State Remarks Signal/direction
Near end
System
B
Far end
PBX
High-
resistance
loop
Low-resistance loop
High-resistance loop
High-resistance loop
Ground
on tip/
battery
on ring
Ground on tip/
battery on ring
Ground on tip/
battery on ring
Battery on tip/
ground on ring
Terminal A goes off hook and dials access
code. Near end reverses battery and ground
on tip and ring, alerting far end.
Far end detects battery/ground reversal and
answers call by placing a low resistance
between tip and ring.
Near end monitors loop current during 2-way
voice connection.
If far end disconnects first, it opens the loop.
Near end detects drop in loop current and
reverses battery and ground on tip and ring.
If near end disconnects first, it reverses
battery and ground on tip and ring.
Far end detects battery/ground reversal and
opens loop.
553-AAA1148
Idle
Idle
Idle
Trunk seizure
B goes on hook
A goes on hook
2-way voice
connection