7841 SIP Phone line disappears then reappears

[Mark Verwey]

We have started having some of the 7841 phones with multiple lines configured on them have the first line (top left on display) suddenly disappear then reappear.  The other lines don't do this.  However when this does occur the phone does allow you to answer a call regardless of if you pickup the handset or use the speaker or headset button.  It will ring then go to voicemail, the calling party thinks you just didn't answer the call.  This has happened to a couple of these phones, we have rebooted them and they started working properly and also done a factory reset on them.  Regardless of what we do, after about a month they do this until the phone is rebooted or reset.  I am running firmware version  sip78xx.11-7-7-17.  I have other phones running version sip78xx.11-0-1-11. 

[Ratheesh Kumar]

Hi there

There has been a couple of weird issues for 7800 series phones while answering calls. You could try upgrading the firmware to the latest 12.0 or 12.1 versions. Try for a couple of phones initially and then roll out if the issue is fixed. Else you might need to open up a TAC and grab a hot fix.

Hope this helps!

Cheers
Rath!

***Please rate helpful posts***

[Mark Verwey]

I did the firmware upgrade to 12.1 and was hopeful but after about 3 hrs the problem showed its ugly head again.  I guess now its time to open a case with TAC.  Wish me luck...I will update this post once I have a solution in place.

[Manish Gogna]

Hi Mark,

You may share the following details with the TAC engineer:

Are all these phones on the same site / connected to same switch?

Did they ever work fine on a lower firmware version?

If you swap one of these phones with another phone model, does the issue appear on that new phone ( model ) as well?

You may be required to share the pcaps from the switchport to which the phone is connected or the debugs from the phone in case there is no existing bug for this issue.

HTH

Manish

[Mark Verwey]

Thanks for this information, I will collect as much as I can before I open the case with TAC.  The phones are located across our entire campus.  Most aren't connected to the same switch but they are all the same model switch (Cisco 3850).  We never had this sort of problem with the Cisco 7942/62 series phones.  About a year ago we upgraded all the phones to 7841's which is when this issue started occurring.  At first I thought it was just an isolated incident with a phone that was bad from the start.  But in the past year we have had about a dozen phones do this and the problem does seem to go away if we replace the phone.

[Ratheesh Kumar]

Hi there

I bet TAC should be your next step. There are numerous bugs with 7800 answering issues and most of them got fixed by Cisco releasing a new ES version.

Hope this Helps

Cheers
Rath!

***Please rate helpful posts***