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Specifications
Release 3.3 85
OPS Line Card Message Waiting Switches
Eight message waiting switches (S1 through S8) are mounted on the OPS card. These switches
are used to select the type of message-waiting signaling employed on each of the eight OPS
line card circuits. Each circuit provides two message-waiting switch types.
Operation
Calls incoming to the OPS line card are converted from analog to digital signals by a line circuit
module. The call is then switched and the two parties connected. All signals are passed through
the 2-wire to 4-wire hybrid circuit on the line circuit module. The line busy status LED is turned
on (lit) while the call is in progress.
Calls outgoing on the OPS line card are converted from digital signals to analog signals by a
line circuit module. The main control processor oversees the connection between the two
OPS Line Card Specifications
Variants Available: A-law (UK), µ-law (NA)
Number of Circuits per Card: 8 OPS Circuits
Power Consumption: UK: 8.53 Watts
NA: 8.67 Watts
External Loop Resistance: 1800 ohms maximum
External Wire Resistance: 1600 ohms maximum
External Loop Length: 5853 meters (19022 ft.), 26 AWG (27 IWG)
15240 meters (49530 ft.), 22 AWG (23 IWG)
Minimum Conductor Leakage: 1500 ohms
Loop Detector Threshold: 12 mA (+1 mA)
Trip Battery Silent Interval: -50 Vdc nominal
Trip Battery Ringing Interval: -50 Vdc nominal
Bridged Ringers: 5 (C4 or equivalent)
Ringing Voltage and Frequency: 82 to 90 Vrms, 17 to 25 Hz
Features Provided: 2-wire/4-wire conversion
A-D/D-A Conversion
DC Loop Supervision and Dial Pulse Collection
Ground Button Detection and Ring Lead
Current Limiting
Self-Test Capability
Automatic Card Identification
Compliance: Complies with all pertinent sections of EIA Standard RS-464.
Message-Waiting Switch Types
Setting Description
A Circuits are connected to OPS lines. Loop extended over the Message-Waiting Answer
(MWA)/ Message-Waiting Busy (MWB) pair to the called extension.
B Circuits are connected to ONS lines. Consists of a -140 Vdc source delivered at a variable
rate to the Ring lead of the called extension. Rate is custom programmed to be
continuously on through 80 Hz.