Nortel Networks 553-3001-211 manual 576 of 894 NT8D14 Universal Trunk card

Page 576 of 894 NT8D14 Universal Trunk card

Figure 123

Two-way, loop DR, TIE trunk call connection sequence – incoming call from far-end PBX

A			Near end				Far end		B
			System				System
	State				Signal/direction				Remarks
				Ground on tip/		Ground on tip/
		Idle		battery on ring		battery on ring
					Low-resistance loop
Trunk seizure								Far end places a low resistance between tip and ring.
								Near end detects increase in loop current and makes
					Address signaling			trunk busy to all outgoing calls.
Outpulsing								Far end applies addressing to the trunk in the form of
				Ringback				battery-ground or loop pulsing, or DTMF tones.
	A rings							Near end detects addressing, alerts terminal A, and
				Battery on tip/
								provides ringback tone to far end.
2-way voice				ground on ring				When terminal A goes off hook, near end trips ringback
connection
								tone and provides answer supervision, if required by far
								end, by reversing battery and ground on tip and ring.
B goes on hook					High-resistance loop			If far end disconnects first, it momentarily opens the loop
								and then restores normal battery and ground if no near-
								end answer supervision was provided when call was
				Ground on tip/				establish-ed. Otherwise, it waits for the near end to
								restore normal battery and ground.
				battery on ring				Near end detects drop in loop current and restores normal
						Ground on tip/		battery and ground if answer supervision was provided.
								Otherwise, terminal A simply hangs up.
		Idle				battery on ring		If answer supervision was provided, far end restores
								normal battery and ground when it detects
								battery/ground reversal from near end.
				Ground on tip/
A goes on hook				battery on ring				If near end disconnects first, normal battery is restored if
								answer supervision was provided to establish call.
						Ground on tip/		Otherwise, terminal A simply hangs up.
		Idle				battery on ring		If far end detects battery/ground reversal, it
								momentarily opens loop and then restores normal
								battery. But, if no answer supervision was provided by
								the near end when the call was established, it cannot
								supply a battery reversal to signal call termination; the
								person at terminal B must recognize end of call and
								hang up, which will then cause the far end to restore
								normal battery.		553-AAA1140

553-3001-211 Standard 2.00 September 2004