Nortel Networks Circuit Card Manual De Usuario

 NT1R20 Off-Premise Station Analog Line card

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 
connection

When call is answered, ringback tone is 
removed, and call is put through to 
far-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.