Nortel Networks Video Gaming Accessories 553-3001-211 Manuale Utente

 NT8D14 Universal Trunk card

Idle

Idle

B rings

Trunk seizure

Dial tone from CO

B goes on hook

Idle

A goes on hook

Near end

System

Far end

CO

Tip open/

battery

 on ring

Tip open/

battery on ring

Ringback

Tip open/

battery on ring

High-
resistance
loop

Ground on ring

When the CO recognizes seizure, it grounds the tip 
and supplies dial tone.

When terminal B answers, ringing is tripped and CO 
cuts terminal B through to trunk. Some COs may 
reverse battery and ground on tip and ring when 
terminal B answers or for toll denial.

Upon receipt of the first pulse/tone, the CO removes 
dial tone. When outpulsing is complete, terminal B is 
rung (if idle) and the proper audible indication is 
returned to local end.

If far end disconnects first, CO removes ground from 
tip. If battery and ground were reversed when call 
was established, battery is removed from tip and 
restored to ring.

Near end detects drop in loop current and opens loop.

Digits are outpulsed in the form of a series of loop 
pulses or DTMF tones.

2-way voice

connection

Ground on tip/

battery on ring,

dial tone

Low-resistance loop

High-resistance loop

High-resistance loop

Address signaling

Detection of the ground on tip is signaled to the CE 
via the data input bus. The CE then sends a signal via 
the data output bus to place a low-resistance loop 
across the tip and ring and remove ground from ring.

Terminal A dials trunk access code. CE sends a 
message via the data output bus to ground the ring.  

If near end disconnects first, it opens the loop.

CO detects drop in loop current and removes ground 
from tip. If battery and ground were reversed when 
call was established, battery is removed from tip and 
restored to ring.

553-AAA1136