Trunk Types Description - Nortel Meridian 1 Manual

Page 8 of 44 NT5K93 Central office trunk circuit card
Table 6T
NT5K18BA loss values

Trunk types description

Ground start operation
Supplement to 553-3011-210
Central office line
loss
0 to 3 dB
3 to 6 dB
Each NT5K18BA Central office trunk card unit is capable of operating as
one of the following:
• Central office - Ground Start
• Central office - Loop Start
Ground start operation is configured in software and implemented through
software download messages.
Idle State
In the idle state, a ringing detector is connected across the tip and ring leads.
The capacitance between the tip and ring leads is 1.8 µF with a resistance
greater than 5 kΩ. The central office applies -50V to the ring wire, while the
tip wire is open circuit.
Call placed by Option 11
The Option 11 places a call by establishing a dc path between the tip and ring
leads and applying ground to the ring wire. The central office acknowledges
by applying ground to the tip wire and returning dial tone. When dial tone is
received, the Option 11 removes ground from the ring lead.
Dialling
The Option 11 sends digits in the form of loop disconnect signalling or Dual
Tone Multi-frequency (DTMF) digits.
Answer
When the called party answers, the central office reverses polarity on the line.
The Option 11 interprets the polarity reversal as an answer signal.
Provisional 1.3
Analog to Digital
loss
-6 dB
-8 dB
July 1993
Digital to Analog loss
0 dB
-3 dB