Nortel Networks 553-3001-211 manual NT1R20 Off-Premise Station Analog Line card

		NT1R20 Off-Premise Station Analog Line card		Page 169 of 894
Table 68
Call connection sequence—near-end station receiving call (Part 2 of 2)
	Signal / Direction
State	Far-end / Near-end		Remarks
Outpulsing	Addressing signals		Near-end station dials number (loop
			pulsing or DTMF tones).
			The system detects start of dialing and
			remove dial tone.
	Ringback (or busy)		The system decodes addressing, route
			calls, and supply ringback tone to
			near-end station if far-end is on-hook.
			(Busy tone is supplied if far-end is
			off-hook).
Two-way voice			When call is answered, ringback tone
connection			is removed, and call is put through to
			far-end station.
Near-end station	High resistance loop		If near end station hangs-up first, the
hangs-up first			line card detects the drop in loop
			current.
Line card unit idle	Group on tip, battery on ring		Line card unit is ready for the next call.
	High resistance loop
Far end station	High resistance loop		If the far-end hangs-up first, the system
hangs up first			detects disconnect signalling from the
			trunk. The person at the near-end
			recognizes the end of the call and
			hangs-up.
Line card unit idle	Ground on tip/battery on ring		Line card unit is ready for the next call.
	High resistance loop

Circuit Card Description and Installation