Cisco Support Community
Community Member

T1 2/0 is down. (Line Looped (inband CSU code))


I just installed a new T1 card on my 3640 and I am getting this. Could someone tell me what it means and how to fix it?

This is the hole result:

CCoVoIP#show controller t1 2/0

T1 2/0 is down. (Line Looped (inband CSU code))

Applique type is Channelized T1

Cablelength is short 133

Description: Connection to Switch #18

Receiver has loss of signal.

alarm-trigger is not set

Version info Firmware: 20020812, FPGA: 11

Framing is SF, Line Code is AMI, Clock Source is Line.

Data in current interval (0 seconds elapsed):

0 Line Code Violations, 0 Path Code Violations

0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins

0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs

Thanks in advance.


Re: T1 2/0 is down. (Line Looped (inband CSU code))

This is not a configuration problem and the line seems to be fine. However the "Line Looped (inband CSU code)" message is actually triggered by a Telco loopback or by the far end device sending a loopback.

1. Verify in the remote end the configuration and make sure there's no remote loopback in

progress or configured in teh controller/interface.

2. Verify with Telco that they have no loopback sent to the controller.

Community Member

Re: T1 2/0 is down. (Line Looped (inband CSU code))

I had no Telco or any other thing connected so I supposed the card was bad and send it back to get replaced.

Thank you for your help.


CreatePlease to create content