Panasonic KX-T336 System Reference Manual page 1492

3.38 Digital trunk failure (frame trouble)
Error Code
Possible cause of
the malfunction
Countermeasures
Note
75xx xx=01 to 42 : Slot number
On booting-up of T-1/E-1 card (physical number xx), it failed to synchronize with
the clock time sent from the Central Office.
Confirm that the setting of "Frame Sequence" and "Line
Cording" are matched with that of the leased lines.
If not, change the setting of your KX-T336 and CSU.
Then check the clock mode.
Check the cabling between "T-1/E-1 and CSU" and "CSU
and NIU." If not properly cabled, change the cabling.
Execute Loopback Test(Internal).
Test Results NG
Replace the T-1/E-1
card with a new one.
Execute Loopback Test(External: between KX-T336 and
CSU)
OK
Check the CSU. If not good, replace it with a new one.
Ask the T-1/E-1 carrier to check the line conditions.
Or, check the equipment in other switching system which
your T-1/E-1 lines are connected with.
Another T-1/E-1 card with next priority will work as a master card, if more than
two T-1/E-1 cards were registered to the system by CLP command (Refer to
Section 64.03) beforehand. Otherwise, the system will synchronize with the
system internal clock.
14-E-37-4
NG
NG
Test Results
OK
NG
NG
End
(70695)
OK
OK
OK