Nortel Networks 553-3001-211 manual NT8D14 Universal Trunk card Page 581

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-AAA1142

Circuit Card Description and Installation

If answer supervision is provided by far end, reverse battery and ground are applied to tip and ring when terminal B answers.

Terminal A dials and battery-ground or loop pulses, or DTMF tones, are sent to far end.

When terminal A goes off hook, near end places a low resistance between tip and ring.

Remarks

NT8D14 Universal Trunk card Page 581 of 894

Figure 127

Two-way, loop DR, TIE trunk call connection sequence – outgoing call to far-end PBX

A		Near end					Far end
			System					PBX
	State				Signal/direction
				Ground on tip/		Ground on tip/
	Idle			battery on ring		battery on ring
				Low-resistance loop
Trunk seizure
				Address signaling
Outpulsing
B rings						Battery on tip/
2-way voice						ground on ring
connection

B

A goes on hook

High-resistance loop

Ground on tip/ battery on ring

Ground on tip/ battery on ring

Idle

B goes on hook

Ground on tip/ battery on ring

Ground on tip/

battery on ring

Idle