Application; Loop Start Operation; Ground Start Operation; Direct Inward Dial Operation - Meridian Nortel 1 Option 11C Technical Reference Manual

Application

Loop start operation

Ground start operation

Direct Inward Dial operation

The optional applications, features, and signaling arrangements for each
trunk are assigned through unique route and trunk data blocks.
Loop start operation is configured in software and is implemented in the card
through software download messages. When the Universal Trunk is idle, it
provides a high impedance toward the CO for isolation and AC detection. The
alerting signal is 20 Hz ringing sent by North American CO. When an
incoming call is answered, ringing is tripped when the trunk places a low
resistance DC loop towards the CO.
For outgoing calls from a telephone set or attendant console, software sends
an outgoing seizure message to place a low resistance loop across the tip and
ring leads towards the CO. When the CO is ready to receive digits, it returns
dial tone. The outward address signaling is applied from the system in the
form of DTMF tones or dial pulses.
Ground start operation is configured in software and implemented through
software download messages. In an idle state, the tip conductor from the CO
is open and a high resistance negative battery is present on the tip of the trunk.
This biases the tip ground detector OFF until the CO places ground on the tip
at seizure. After the tip ground is detected, the Universal Trunk Card scans
for a ringing detection signal before presenting the call to an attendant and
tripping the ringing. A low resistance is placed across the tip and ring
conductors and a speech path is established.
An incoming call from the CO places a low resistance loop across the tip and
ring leads. Dial pulses or DTMF signals are then presented from the CO.
When the call is presented and the terminating party answers, the Universal
Trunk Card reverses battery and ground on the tip and ring leads to the CO.
The trunk is arranged for first party release. The CO releases the trunk by
removing the low resistance loop and normal battery and ground are restored
at the system.
NT8D14 Universal Trunk Card
Option 11C and 11C Mini
Page 385 of 544
Technical Reference Guide