Avaya S8700 Maintenance Manual page 660

Maintenance Object Repair Procedure
VC-DSP Port DSP Loop-Back Test (#1105)
This test is destructive.
This test verifies the connectivity of a VC-DSPPT across the TDM bus. It aborts if
calls associated with the port are in progress. Failure of this test indicates an
on-board fault associated with the port hardware on the circuit pack.
Figure 8-61. VC Circuit pack DSP Port DSP Loop-Around Test
8-1356 Issue 1 May 2002 555-233-142