Nortel Networks 1000 - Manual (Page 128)

128 NT1R20 Off-Premise Station Analog Line card
Table 54
Call connection sequence-near-end station receiving call
State
Signal / Direction
Far-end / Near-end
Remarks
Line card unit idle Group on tip, battery on ring
High resistance loop No battery current drawn.
Far-end station goes off-hook and
addresses (dials-up) the near-end station.
The system receives the incoming call on a
trunk and determine the TN.
Incoming call Ringing The system applies 20 Hz ringing to ring
lead.
Near-end station
off-hook Low resistance loop
Two-way voice
connection The system detects increase in loop
current, tips ringing, and put call through to
near-end station.
Near end station
hangs up first High-resistance loop If near end station hangs-up first, the line
card detects the drop in loop current.
Line card unit idle Group on tip, battery on ring
High resistance loop Line card unit is ready for the next call.
Far end station
hangs up first High resistance loop If the far-end hangs-up first, the system
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
High resistance loop Line card unit is ready for the next call.
Incoming calls to a telephone connected to the NT1R20 OPS Analog Line
Card originate from stations that can be local (served by the CS 1000)
or remote (served through the public switched telephone network). The
alerting signal to telephones is 20 Hz (nominal) ringing. When an incoming
call is answered, ringing is tripped as the telephone goes off-hook, placing
a low-resistance dc loop across the tip and ring leads toward the OPS
analog line card.
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 02.06 Standard
27 August 2008
Copyright © 2003-2008 Nortel Networks
.