Nortel Enterprise 1000 Reference Manual page 76

Page 76 of 236 Analog Trunk Cards - NT8D14 Universal Trunk Card
Figure 28
Two-way, loop OAID, tie trunk call states – incoming call from far-end PBX
A
Near-end
Succession
CSE 1000
State
Idle
Trunk seizure
Outpulsing
A rings
2-way voice
connection
B goes on hook
Idle
A goes on hook
Idle
553-3023-211 Standard 1.00 June 2001
Signal/direction
Ground
on tip/
battery
resistance
on ring
Low-resistance loop
Address signaling
Battery on tip/
ground on ring
High-resistance loop
Ground on tip/
battery on ring
Ground on tip/
battery on ring
High-resistance loop
Far-end
CO
High-
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.
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 far-end disconnects first, it opens the loop.
Near-end detects drop in loop current and
restores normal battery and ground.
If near-end disconnects first, it reverses
battery and ground on tip and ring.
Far-end detects battery/ground reversal and
opens loop.
B
Remarks
553-CSE6252