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DEFINITY Enterprise Communications Server Release 5
Maintenance and Test for R5vs/si
555-230-123
Issue 1
April 1997
Maintenance Object Repair Procedures
Page 10-444DID-TRK (DID Trunk)
10
Figure 10-25. DID Trunk Interactions
For each call, the CO switch signals the system by opening and closing
individual DID loops (one of the eight ports) and causing the starting or stopping
of loop current.
A DID trunk operation involves three significant aspects:
1. Transmission—deals with the interface requirements regarding all AC
signals. Transmission includes gain, analog to digital encoding, and
digital to analog decoding.
2. Signaling—involves interpretation of DC signals appearing on Tip and
Ring to and from the CO. These signals include off-hook, on-hook, and
dial pulse detection.
3. Switch Connection—involves the connection between the trunk circuitry
and the TDM Bus of the system. It operates the switchhook connection to
the TDM Bus.
Four tests are implemented to diagnose the health of a DID trunk. All of them test
on-board circuitry only. They are:
1. Loop Around and Conference Circuit Test—verifies the transmission
operation of the circuit pack (loop around within the port), and checks the
conference capabilities of all ports.
This test may fail due to noise induced by adjacent electric power lines.
Customers having this problem should resolve it with their local power
company. To temporarily alleviate the alarm caused by the failure of this
test, the test may be disabled from trunk administration Test field. (This
also disables the port diagnostic test).
2. NPE Crosstalk Test—verifies the switch connection operation of the circuit
pack. The test also verifies that the trunk circuitry only talks on the
selected time slot on the TDM Bus and never crosses over to time slots
reserved for other connections.
DID
TRUNK
INCOMING
CALLS ONLY
OFFICE
SWITCH
1
8
CENTRAL
"DEFINITY"
COMMUNICATIONS
SYSTEM