Nortel Enterprise 1000 Reference Manual page 69

Figure 23
Two-way, loop DR, tie trunk call states – outgoing call to far-end PBX
Note: Where no far-end answer supervision is provided, party at near-end hangs
up after recognizing far-end call termination.
Succession Communication Server for Enterprise 1000 Circuit Card Reference Guide
Analog Trunk Cards - NT8D14 Universal Trunk Card
Succession CSE 1000
Ground on tip,
battery on ring
Idle
Near-end
originates
Near-end
hangs up
(Note)
(near-end)
Low-resistance
loop
Near-end
disconnects
first
Battery-ground
or loop pulse
or DTMF
Far-end
answers
(no ans sup)
Far-end
answers
(ans sup)
Page 69 of 236
High-resistance
loop
Near-end
disconnects
Far-end
disconnects
Far-end
disconnects
first
Near-end
disconnects
first
553-CSE6247