Paradyne 3150 Operator's Manual page 107

Line Loopback (LLB)
The Line Loopback command (LLB) loops the received signal on the network
interface (NI) back to the network without change.
Procedure
To perform a Line loopback:
3150-A2-GB24-10
1. From the top-level menu screen, select Test.
2. From the Test screen, select Lpbk.
Test:
Rlpbk Lpbk
F2
F1
3. From the Loopback screen, select LLB.
Loopback:
Abort LLB
F2
F1
Test Started appears on Line 2. If a line loopback is already in progress,
the Already Active message appears. If an invalid combination of
loopbacks is in progress, the error message Invld Test Combo appears
(see Table 8-2, Valid Loopback
combinations).
March 2001
Ptrns
F3
PLB
F3
Combinations, for valid loopback test
8. Testing
8-7