Nortel Networks 553-3001-211 manual 590 of 894 NT8D14 Universal Trunk card

Page 590 of 894 NT8D14 Universal Trunk card

Figure 134

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

A		Near end				Far end			B
		System					PBX
	State			Signal/direction					Remarks
			Ground
			on tip/		High-
			battery		resistance
	Idle		on ring			loop
			Battery on tip/
Trunk seizure			ground on ring					Terminal A goes off hook and dials access
								code. Near end reverses battery and ground
								on tip and ring, alerting far end.
2-way voice					Low-resistance loop			Far end detects battery/ground reversal and
connection
								answers call by placing a low resistance
								between tip and ring.
								Near end monitors loop current during 2-way
								voice connection.
B goes on hook					High-resistance loop			If far end disconnects first, it opens the loop.
			Ground on tip/
	Idle		battery on ring					Near end detects drop in loop current and
								reverses battery and ground on tip and ring.
			Ground on tip/
A goes on hook			battery on ring					If near end disconnects first, it reverses
					High-resistance loop			battery and ground on tip and ring.
	Idle							Far end detects battery/ground reversal and
								opens loop.
									553-AAA1148

553-3001-211 Standard 2.00 September 2004