NT8D09Analog Message Waiting Line Card Page373 of 544
Option11C and 11C Mini TechnicalReference Guide
Functional
The analog message waiting line card contains a microprocessor that provides
the following functions:
•self-identification
•self-test
•control of card operation
•status report to the controller
•maintenance diagnostics
The analog message waiting line card also provides:
•600-ohm balanced terminating impedance
•analog-to-digital and digital-to-analog conversion of transmission and
reception signals for 16 audio phone lines
•transmission and reception of scan and signaling device (SSD) signaling
messages over a DS30X signaling channel in A10 format
•on-hook/off-hook status and switchhook flash detection
•20-Hz ringing signal connection and automatic disconnection when the
station goes off-hook
•synchronization for connecting and disconnecting the ringing signal to
zero crossing of ringing voltage
•loopback of SSD messages and pulse code modulation (PCM) signals for
diagnostic purposes
•correct initialization of all features at power-up
•direct reporting of digit dialed (500-type telephones) by collecting dial
pulses
•connection of -150 V DC at 1 Hz to activate message waiting lamps
•lamp status detection
•disabling and enabling of selected units for maintenance