Nortel Networks 553-3001-211 manual NT8D14 Universal Trunk card Page 571

553-AAA1136

NT8D14 Universal Trunk card Page 571 of 894

Figure 119

Ground start call connection sequence – outgoing call to CO/FX/WATS

ANear end System

Far end B

CO

State

Idle

Trunk seizure

Dial tone from CO

B rings

2-way voice connection

B goes on hook

Idle

A goes on hook

Idle

	Signal/direction			Remarks
High-		Tip open/
resistance		battery
loop		on ring
Ground on ring			Terminal A dials trunk access code. CE sends a
		Ground on tip/	message via the data output bus to ground the ring.
		battery on ring,
		dial tone	When the CO recognizes seizure, it grounds the tip
Low-resistance loop			and supplies dial tone.
			Detection of the ground on tip is signaled to the CE
			via the data input bus. The CE then sends a signal via
			the data output bus to place a low-resistance loop
Address signaling			across the tip and ring and remove ground from ring.
			Digits are outpulsed in the form of a series of loop
		Ringback	pulses or DTMF tones.
			Upon receipt of the first pulse/tone, the CO removes
			dial tone. When outpulsing is complete, terminal B is
			rung (if idle) and the proper audible indication is
			returned to local end.
			When terminal B answers, ringing is tripped and CO
			cuts terminal B through to trunk. Some COs may
			reverse battery and ground on tip and ring when
			terminal B answers or for toll denial.
		Tip open/
		battery on ring	If far end disconnects first, CO removes ground from
			tip. If battery and ground were reversed when call
			was established, battery is removed from tip and
High-resistance loop			restored to ring.
			Near end detects drop in loop current and opens loop.
High-resistance loop
			If near end disconnects first, it opens the loop.
		Tip open/
		battery on ring	CO detects drop in loop current and removes ground
			from tip. If battery and ground were reversed when
			call was established, battery is removed from tip and
			restored to ring.

Circuit Card Description and Installation