Nortel Networks Video Gaming Accessories 553-3001-211 Manuale Utente
Page 574 of 894
NT8D14 Universal Trunk card
Figure 121
DID trunk, loop DR call connection sequence – incoming call from CO
DID trunk, loop DR call connection sequence – incoming call from CO
A
State
Idle
Idle
Trunk seizure
Outpulsing
A rings
B goes on hook
Idle
A goes on hook
Remarks
Signal/direction
Near end
System
B
Far end
CO
High-
resistance
loop
Address signaling
High-resistance loop
High-resistance loop
Ground
on tip/
battery
on ring
on tip/
battery
on ring
Ground on tip/
battery on ring
battery on ring
Ground on tip/
battery on ring
battery on ring
Low-resistance loop
CO places a low resistance between tip and
ring.
ring.
Near end detects increase in loop current
and makes trunk busy to all outgoing calls.
and makes trunk busy to all outgoing calls.
CO applies addressing to the trunk in the
form of battery-ground or loop pulses or
DTMF tones.
form of battery-ground or loop pulses or
DTMF tones.
Near end detects addressing, alerts terminal
A, and provides ringback tone to CO.
A, and provides ringback tone to CO.
If far end disconnects first, CO opens the
loop.
loop.
Near end detects drop in loop current and
reverses battery and ground on tip and ring.
reverses battery and ground on tip and ring.
2-way voice
connection
Battery on tip/
ground on ring
ground on ring
Ringback
When terminal A goes off hook, near end
trips ringback tone and provides answer
super-vision by reversing battery and ground
on tip and ring.
trips ringback tone and provides answer
super-vision by reversing battery and ground
on tip and ring.
If near end disconnects first, it reverses
battery and ground on tip and ring.
battery and ground on tip and ring.
CO detects battery/ground reversal and
opens loop.
opens loop.
553-AAA1138