Line Interface Units; Card Control Functions - Avaya Nortel Communication Server 1000 Reference

NT8D09 Analog Message Waiting Line card

Line interface units

The analog message waiting line card contains 16 identical and independently configurable
line interface units (also referred to as circuits). Each unit provides 600-ohm impedance
matching and a balance network in a signal transformer/analog hybrid circuit. Circuits are also
provided in each unit to apply the ringing voltage onto the line synchronized to the ringing
current zero crossing. Signal detection circuits monitor on-hook/off-hook status and switchhook
flash detection. Four codecs are provided to perform A/D and D/A conversion of line analog
voiceband signals to digital PCM signals. Each codec supports four line interface units. The
following features are common to all units on the card:
• Transmission and reception of Scan and Signaling Device (SSD) signaling messages
over a DS30X signaling channel in A10 format.
• Loopback of SSD messages and pulse code modulation (PCM) signals for diagnostic
purposes.
• Correct initialization of all features, as configured in software, at power-up.
• Direct reporting of digits dialed (500 telephones) by collecting dial pulses.
• Connection of –150 V DC at 1 Hz to activate message waiting lamps in two telephones
in parallel. The two telephones must be the same type or the neon series resistor in each
telephone must be 54 K ohms or greater.
• Lamp status detection (does not detect a failure of either lamp when operating in
parallel).
• Disabling and enabling of selected units for maintenance.
• 40 mA to telephones with short circuit protection.

Card control functions

Control functions are provided by the following:
• a microcontroller
• a card LAN interface
• signaling and control circuits on the analog message waiting line card
368 Circuit Card Reference
Comments? infodev@avaya.com
July 2011