UC540 FXO port lockout

Answered Question
Mar 30th, 2010

I am having an issue with the FXO ports on a uc540. Occasionally the port does not release after you hang up a phone call. The call disconnects, but the green light remain lit and no other calls can be placed at that line. Obviously it is causing problems because the phone line on that port becomes inoperable and must be shutdown and turned up to start working again. Here are the results of the show voice call summary during the lockout.

0/0/0         -          -  -                     FXSLS_ONHOOK
0/0/1         -          -  -                     FXSLS_ONHOOK
0/0/2         -          -  -                     FXSLS_ONHOOK
0/0/3         -          -  -                     FXSLS_ONHOOK
0/1/0         -          -  -                     FXOLS_REMOTE_RELEASE
0/1/1         -          -  -                     FXOLS_REMOTE_RELEASE
0/1/2         -          -  -                     FXOLS_ONHOOK
0/1/3         -          -  -                     FXOLS_ONHOOK
0/4/0         g711ulaw   n  S_CONNECT             EM_CONNECT

port 0/1/0 and 0/1/1 are the ports in question. I have not seen this behavior before in any of the UC520, UC540 or UC560's that I have dealt with and I am assuming that it is a carrier issue. Not sure what to look for. Any advise would help.

I have this problem too.
0 votes
Correct Answer by Steven Smith about 6 years 6 months ago

You should read this document.


Find out what type of disconnect the telco is using, and then you will be able to make this work.

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Overall Rating: 5 (1 ratings)
Dan Smith Fri, 04/02/2010 - 12:22

No ideas???? I saw another thread regarding this issue and there weren't any suggestions or solutions there either.

Andrew Hickman Tue, 04/06/2010 - 02:08

Hi Dan,

We've also seen in places like the UK that you need to tune the following command to ensure that the line is properly released at the end of a call:

timing sup-disconnect nn (more detail here)


Dan Smith Wed, 04/07/2010 - 09:53

Thanks for checking back. It hasn't done it for the last week or so, so I'm keeping my fingers crossed.

Andrew Hickman Wed, 04/07/2010 - 10:15

Glad to hear that Dan,

To help us improve the solution in the future, could you let me know the following:

Which country are you in:

What Telco are you using:

What commands to you end up using to fix this:

Many thanks



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