UC520, SIP 7975 still ringing after call transfers to voicemail or hangs up

Answered Question
Sep 21st, 2010
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Hi -

I'm looking for some help, since I can't explain/understand/... why the following is happening.

I have converted my 7975's (2) plus a 7911 to SIP 8.5.3 on my UC 520.

Inbound calling is working

Outbound calling is working

I can not call internally from the 7975 to the 7911, but I can call the other way (791 to 7975).

But more importantly, and the main reason for this post ...

When I call the 7975's, after the timeout it goes to voice mail, as expected, but the screen still looks like the extension is rining (phone icon off the hook, and caller id info still displayed). This happens for an internal call (7911 to 7975) as well as for an external call to the parallel hunt group. The only way I can get the phone to stop displaying the caller id info, and the screen to change back to what it looks like before a call is to power cycle the phone.

A reset and/or restart do not help.  Also, if I try calling the extension again, it doesn't go through...I get an 'error' sound.  If I call from the 7911 and pick up the 7975, then hang up. The call disconnects properly.

ANY help would be appreciated.


Correct Answer by Felipe Garrido about 6 years 10 months ago

OK, I see the signaling now. The phone and CME look to be exchanging the correct signaling until after the 487 is ACK'd. This looks to be a phone issue. Would you be wiling to upgrade to the latest firmware,9.0(2)SR2, and test again?


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Overall Rating: 5 (1 ratings)
Felipe Garrido Tue, 09/21/2010 - 10:29
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Can you collect the following debugs,

debug ccsip message

debug voip ccapi inout

Please note the calling and called party numbers

Also, include the current running configuration and the following command output.

show voice register all



gregatatt Tue, 09/21/2010 - 11:19
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I will collect and post.....

In the mean time, while searching futher, I've found ....


Got a new Cisco 7975G IP Phone, I even made an iPad style service menu for it, Its running SIP 8.5.2SR1, if you upgrade beyond this version it keeps on ringing forever AND if you use an older version the time &  date shows up as sometime in 2008 -

Also ....


I'm pretty new to useing Trixbox and therefore I can't decide whether  my problem is Trixbox related or Cisco 7975G related... (I assum the  first one...).

If someone calls from any phone to my Cisco 7975 (which is behind a  pretty default installation of Trixbox 2.8), and they hang-up before I  picked up my 7975, the incoming line keeps blinking as if the phone is  still ringing. I have to press CFwdALL to stop the line from blinking  and if I try to make a phonecall while the line is still blinking, the  phone opens a new line and keeps the blinking one, blinking...

It is as if the phone doesn't understand (or receive a signal telling the phone) that the caller hung up.

I hope anybody has an idea...

Many thanks in advance for your help!

gregatatt Tue, 09/21/2010 - 11:55
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attaching ...

debug.log  (debug output)

SHOWRUN.log ( running config)

SHOWVOICEREGISTER.log (show voice register all output)

Called from 2124561355

Called to AA (6199)

AA Option 6 forwards to Blast Group 7301

After no ans timeout, Blast group forwards to mailbox 84201



Felipe Garrido Wed, 09/22/2010 - 06:59
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I don't see a 487 being sent after the cancel when the call hits the 16 second timeout on the hunt group but I also see messages getting dropped. Can you collect the debugs again but this time to the logging buffer?

Configure the following first.

no logging console

no logging monitor

logging buffer 2000000 debug

service sequence

1. Enable the debugs.

2. Issue the clear log command.

3. Reproduce the issue.

4. Issue the terminal length 0 and show log commands.



Correct Answer
Felipe Garrido Wed, 09/22/2010 - 07:21
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  • Cisco Employee,

OK, I see the signaling now. The phone and CME look to be exchanging the correct signaling until after the 487 is ACK'd. This looks to be a phone issue. Would you be wiling to upgrade to the latest firmware,9.0(2)SR2, and test again?


gregatatt Wed, 09/22/2010 - 08:11
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I'm a big beliver in upgrading to the latest firmware, and would have done that before posting the question, but read somewhere that Cisco didn't support newer firmware on the phones with the UC 520.

I will download and install when I have physical access to the system later today.

I will then install, test and post my results.



gregatatt Thu, 09/23/2010 - 06:08
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Firmware update fixed the problem!

THANKS !!!!!!!



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