![](http://pdfasset.owneriq.net/a/99/a9933c8c-a6bf-409f-96ad-2a6a14b125dd/a9933c8c-a6bf-409f-96ad-2a6a14b125dd-bg175.png)
NT8D09 Analog Message Waiting Line Card Page 373 of 544
Option 11C and 11C Mini Technical Reference 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