Nortel Enterprise 1000 Reference Manual page 70

Page 70 of 236 Analog Trunk Cards - NT8D14 Universal Trunk Card
Figure 24
Two-way, loop DR, tie trunk call connection sequence – outgoing call to far-end PBX
A
Near-end
Succession
CSE 1000
State
Idle
Low-resistance loop
Trunk seizure
Address signaling
Outpulsing
B rings
2-way voice
connection
High-resistance loop
A goes on hook
Idle
B goes on hook
Idle
553-3023-211 Standard 1.00 June 2001
Signal/direction
Ground on tip/ Ground on tip/
battery on ring battery on ring
Battery on tip/
ground on ring
Ground on tip/
battery on ring
Ground on tip/
battery on ring
Ground on tip/
battery on ring
Ground on tip/
battery on ring
B
Far-end
CO
Remarks
When terminal A goes off hook, near-end places a low
resistance between tip and ring.
Terminal A dials and battery-ground or loop pulses, or
DTMF tones, are sent to far-end.
If answer supervision is provided by far-end, reverse
battery and ground are applied to tip and ring when
terminal B answers.
Near-end monitors loop current during 2-way voice
connection.
If near-end disconnects first, it momentarily opens the loop
and then restores normal battery and ground if no far-end
answer supervision was provided when call was establish-
ed. Otherwise, it waits for the far-end to restore normal
battery and ground.
Far-end detects drop in loop current and restores normal
battery and ground if answer supervision was provided.
Otherwise, terminal B simply hangs up.
If answer supervision was provided, near-end restores
normal battery and ground when it detects
battery/ground reversal from far-end.
If far-end disconnects first, it restores normal battery if
answer supervision was provided to establish call.
Otherwise, terminal B simply hangs up.
If near-end detects battery/ground reversal, it moment-
arily opens loop and then restores normal battery. But,
if no answer supervision was provided by the far-end
when the call was established, it cannot supply a
battery reversal to signal call termination; the person at
terminal A must recognize end of call and hang up,
which will then cause the local end to restore normal
battery.
553-CSE6248