88XX offhook/onhook issues

[Andrew Skelly]

Has anybody encountered an issue where your 88XX (specifically 8851) phones have randomly exhibited off-hook/on-hook tendencies?  Over the past year we have had upwards of 250+ phones randomly go off-hook then on-hook in less than a second, sometimes causing active calls to be dropped.  Different hardware and firmware versions but the symptoms are always the same.  TAC hasn't found anything yet, so I'm just trying to gauge if this is an issue others are having.  Thanks.

[bmalakiya]

I am facing this issue as well. This has nothing to do with Corrosion, this mostly happens with 8851 phones only. I took Wireshark logs and there is a clear Disconnect message that goes from the phone which disconnects the ringing call. Has anybody got any resolution ? Also are all of these cases happening to people/setup where they have Cisco's Fabric Network (DNAC, ISE) ?

[nihebe]

A corrosion issue seems plausible from my point of view.

I opened up a CP-8865 and removed the plastic cap of the hook switch. The contacts looked somewhat dirty and I tried to clean them by gently scratching (similar to the "Clean the contacts" recommendation, which seems really inappropriate with a rubber for this kind of switch). By doing so, it seems like I bended the lower contacts farer away from the upper ones, which leads to a completely dysfunctional hook switch - the phone indicates to be on-hook all the time, even if I lift the hook. Well, issue resolved, but now this is a headset-only phone. Anyhow, I think this confirms that the issue is caused by the switch.

Unfortunately, our supplier said the hook switch board is not available as spare part....

[TYFANAN]

Hi fellows, almost a year from last reply, but I am sure there are still people having this issue. After reading a lot and did some experiments I think I found a solution to the offhook/onhook issue. It appears not only with 8851's but in my case mostly with 7861 and 7821. I had the issue with approximately ten phones from the 88xx and 78xx models. Four of them managed to replace during the warranty period, the rest of them fixed by me and my colleagues. First to say CallManager and firmware version are not related to the issue, all the matter in my opinion and experience is the version of hardware at the end of the product ID (PID VID) of the phones, like PID VID CP-7821-K9= V01. After we made a research it appears that all of the problematic phones are V08 and above. So the theory is that in the early phones production were used better materials for hook switch lamellas. We dismantled every hook switch and every one of them had kind of oxidized surface or kind of corrosion, the lamellas were very thin and easy to bend. After gently clean every one of them using contact spray and soft tissues, we bended them carefully just enough so on-hook position the switch opens the circuit and on the other hand off-hook to close the circuit and taking the line.
The last phone 7821 was fixed yesterday. So grab the screwdrivers and cleaning materials, fix and use your phones again!
And of course "78xx plus hook switch board" is not available as a spare part.

[chrsmt50]

Has the problem reoccured in the phones you fixed?

I've run into the same issue with 78XX phones, and have tried bending the contacts under the hookswitch into a better position as well. All of the ones I tried it on still had to be replaced a few weeks later due to the issue reoccuring.

I did not have any contact cleaner though, so that may be the solution here...

[TYFANAN]

The problem didn't reoccur yet. We have two 7861 fixed and in working condition more than 3 months, two 7821 - more than a month and one 8851 in normal working state for more than 2 months. If the issue occur once again, the phones will be dismantle and contacts of the hook switch will be fine tuned. Hope this help.

[Eric Tucker]

Yes its still a confirmed issue I am CM 12.6 expressway 14.2.6 and  yes  PID VID....V09 I simply disconnected the handset and now use it as a speaker phone for now. This new Cisco doc seems very timely document id 45283 message me for a video link of the behavior

[fgeraldo]

Every 1-2 months we have to open RMA because of onhook offhook problems with 7841 phones, they generally are 2-3 years old.

[Joshua Lamb]

if only they had a fix

[Andrew Skelly]

We are actually testing some different firmware versions in conjunction with disabling the handset within the device configuration in CUCM (12.5 SU5).  Hopefully that works, but wouldn't be a viable solution for those that use the handset even on a part-time basis.  It is, however, better then constantly replacing or RMA'ing phones due to the creep corrosion issue, which seems to be never ending at this point.

[Andrew Skelly · Accepted solution]

UPDATE!!!

We've had very positive results with some adjustments to the phones that prevents us from having to replace so many phones for this issue.  Our phone models are 8851 and 8865 so can only speak to those firmware versions, but I'm sure newer firmware on other models will work also.

1 - Update the phone firmware on the impacted device (model 8851 - sip88xx.14-0-1-0001-135, model 8865 - sip8845_65.14-0-1-0001-135)

2 - Disable the handset via Phone Configuration in CUCM

3 - Save, Apply Config, Reset

Hope this helps everybody else!