ADTRAN 1200051L6 - Manual (Page 40)

Chapter 5.Testing
26 ISU 2x64 Dual Port ISDN Service Unit User Manual 61200051L1-1D
The ISU 2x64 must be optioned for Clear Channel operation for DDS
and V.54 loopbacks to take effect.
NEBE/FEBE
This test reports the quality of the network connection between
the T-1 and the switch by viewing the number of near-end block
errors (NEBE) and far-end block errors (FEBE) occurring on the
ISDN interface. An incrementing count in NEBE means the prob-
lem is in the direction of the NT-1. An incrementing count in
FEBE means the problem is in the direction of the switch.
Software Version
This test determines the software version in use on the ISU 2x64.
Loopback Both DTEs
Choosing this option loops back both DTE ports simultaneously.
Test 2047 Both
Choosing this option is similar to Test Remote, except both ports
are tested simultaneously.
Press Cancel to exit any of these options.