Far end phone not disconnected

Unanswered Question
Jul 14th, 2008

Hi NetPro,

For all my cisco phones controlled by CME, when I dial a mobile phone and press the 'EndCall' softkey before it is answered, the mobile keeps ringing.

IF the called phone answered, then disconnecting cisco phone can disconnect the far end.

What can be the problem?


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Overall Rating: 4.3 (4 ratings)
Chuan Liu Tue, 07/15/2008 - 12:35


I am using IOS (C2800NM-ADVIPSERVICESK9-M), Version 12.4(15)T5. All phones are configured with dual-line. The load in use is 7960-7940 P00308000400.


Paolo Bevilacqua Tue, 07/15/2008 - 12:39

I mean the lines going to telco. If FXO, does it happen if you connect a regular phone and try that ?

Chuan Liu Tue, 07/15/2008 - 20:51

Hi Paolo,

The CME is using SIP trunks to a PSTN gateway.

I have just tested a call to phone controlled by another CME (site-2-site IP topology, so no PSTN involved). I got the same result. Terminating the calling party before the called party answers will not stop the called party from keeping ringing. If the call is answered, then terminating the call from the my phone CAN disconnect the far end.

Calls to phones local to the CME have no such an issue.


Paolo Bevilacqua Wed, 07/16/2008 - 00:19


If you take "debug ccsip message" with "term mon" you should see that the CME sends a CANCEL or BYE when hanging up even before the remote answers.

If that is confirmed, the rest of the investigation has to be made on the "pstn gateway".

Chuan Liu Wed, 07/16/2008 - 02:39


You are right. The CME is sending a CANCEL before the remote answers. But after it receives ACK from the remote, it still receives 183 Session Progress, which means the remote has not canceled the call. I tested calls to 3 remote CME's, I had the same results. When I call from the remote CME's, all work fine.

Do you suspect the problem is on the remote CME's?


Paolo Bevilacqua Wed, 07/16/2008 - 02:59

Yes, remote CME should actually cancel the call and that's it.

Which version is the CME with the PSTN lines, and which exact type of lines are these ?

In any case if you switch to H.323 (session protocol cisco) likely it will work fine.

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Chuan Liu Wed, 07/16/2008 - 15:56

Hi Paolo,

The problem was noticed initially when calling a cell phone from the CME (CME-A). Later tests show the problem is also found when this CME is calling other cme's (CME-B) while no PSTN is involved.

I have attached some more debug outputs.

While the debug in CME-A shows sending "CANCEL" and recieving a response, the debug in CME-B does not show any receipt. This might be the problem area.

Both CME's are running CME 4.1(0). IOS is different. CME-B is running c2800nm-advipservicesk9-mz.124-11.XJ4.bin; while CME-a is running c2800nm-advipservicesk9-mz.124-15.T5.bin.

Thanks for your help.

Paolo Bevilacqua Thu, 07/17/2008 - 00:47

Hi, recommend you unify everything to XJ4.

As mentioned before, a possible workaround should be using H.323.

Chuan Liu Thu, 07/17/2008 - 12:32

Thanks Paolo,

I will go with XJ4. I will inform you if that solves the problem.

Thanks again.


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