NT8D09 Analog Message Waiting Line card Page 543 of 894
Circuit Card Description and Installation

Analog line interface

Input impedance
The impedance at tip and ring is 600 ohms with a return loss of:
• 20 dB for 200-500 Hz
• 26 dB for 500-3400 Hz
Insertion loss
On a station line-to-line connection, the total insertion loss at 1 kHz is
6 dB + 1 dB. This is arranged as 3.5 dB loss for analog to PCM, and 2.5 dB
loss for PCM to analog.
Frequency response
The loss values in Table 173 are measured relative to the loss at 1 kHz.
Message channel noise
The message channel noise C-weighted (dBrnC) on 95 percent of the
connections (line to line) with both ends terminated in 600 ohms does not
exceed 20 dBrnC.
Table 173
Analog message waiting line card – frequency response
Frequency (Hz) Minimum (dB) Maximum (dB)
60 20.0 —
200 0.0 5.0
300 –0.5 1.0
3000 –0.5 1.0
3200 –0.5 1.5
3400 0.0 3.0