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1324
Issue 5 October 2002
ISDN Test Call Test (#258)
This test performs a far-end loop around to a far-end switch over an ISDN trunk.
The trunk’s service state must be in-service, maint-NE, or out-of-service/NE, and
no call can be active on the trunk. The test call can be initiated as part of a long
test sequence, or as an individual test, as described below. This test is valid only
for systems using country protocol 1 (including US), or when the far end has
loop-around capability.
A test call connection is established to a far-end switch over the ISDN trunk to be
tested. The digital port on a TN711D Maintenance/Test circuit pack generates a
test-pattern bit stream which is sent to the far-end switch and echoed back. The
received pattern is then compared to the sent pattern and checked for errors that
indicate a loss of integrity on the communications path.
If a test call is running when scheduled maintenance starts, the green LED is
turned off. To determine if a test call is still running, use the list isdn-testcall and
status isdn-testcall commands. A lit yellow LED on the Maintenance/Test circuit
pack also indicates that a test call is running.
There are two methods available to place an outgoing ISDN-PRI test call.
In the first method, the test call connection is established over the TDM Bus of the
transmit and receive sides of the ISDN-PRI trunk to a data channel. This method
is selected when no Maintenance/Test circuit pack resides in the system.
In the second method, the test call connection is established over the TDM Bus of
the transmit and receive sides of the ISDN-PRI trunk to a digital trunk testing port
on the Maintenance/Test circuit pack. The Maintenance/Test Digital Port
generates a pseudo bit stream. A pictorial description of the outgoing ISDN-PRI
test call connectivity is contained in
Figure 38 on page 1325
.