Nortel Networks Circuit Card - Manual (Page 600)

Page 600 of 906 NT8D14 Universal Trunk card
553-3001-211 Standard 3.00 August 2005
Figure 135
Two-way, loop OAID, TIE trunk call connection sequence – incoming call from far-end PBX
A
State
Idle
Idle
Trunk seizure
Outpulsing
A rings
B goes on hook
Idle
A goes on hook
Remarks Signal/direction
Near end
System
B Far end
PBX
High-
resistance
loop
Address signaling
High-resistance loop
High-resistance loop
Ground
on tip/
battery
on ring
Ground on tip/
battery on ring
Ground on tip/
battery on ring
Low-resistance loop
Far end PBX seizes trunk by placing a low
resistance between tip and ring.
Near end detects increase in loop current
and makes trunk busy to all outgoing calls.
Far end sends battery-ground or loop
pulses, or DTMF tones.
Near end detects addressing and alerts
terminal A.
If far end disconnects first, it opens the loop.
Near end detects drop in loop current and
restores normal battery and ground.
2-way voice
connection
Battery on tip/
ground on ring
Terminal A goes off hook. If answer
supervision is required by far end, reverse
battery and ground are applied to tip and ring.
Far end monitors loop current during 2-way
voice connection.
If near end disconnects first, it reverses
battery and ground on tip and ring.
Far end detects battery/ground reversal and
opens loop.
553-AAA1146