7941 phones slow, bad quality , delayed but 8811 phones ok

[chrzan]

Hello,

                 We are having a strange problem our Call Manager is ver 14 and we have a mixture of 7941 and 8811 phones. This has been this way for at least a year this week some of  the 7941 phones began experiencing static , bad quality , robotic sounding. We've tried different firmware the only thing that works is rebooting the phone and it will last about a day and then comes back. Pinging the phones ip address comes back very slow but pinging the computer that plugs into the phone is normal response there is a vlan for data and voice. We did install new switches 2 months ago that is the only difference(replaced 3650 with 9200). Have searched everywhere cannot find anything similar to this. Thanks

[Carlo Poggiarelli]

Hi,

Try an hard reset of one of 7941 phones and see if it becomes responsive.

Please let me know.

Regards

Carlo

[chrzan]

Carlo,

              A reset of phone fixes problem for a day but usually comes back. Thanks 

[Maren Mahoney]

I think @Carlo Poggiarelli is suggesting a factory reset, rather than just a reboot of the phones. Is that what you have already tried? Although, if you have tried different firmware that would imply it is not the firmware.

If the problem is isolated to the phones and the phone VLAN, but PCs connected through the same ports on a different VLAN are okay, that suggests to me that you may have an ip routing problem on the voice vlan.

When you are experiencing the problem, what do the call statistics show on the phone? Are you seeing packet loss and jitter? 

You mention 8811 and 7941 phones. I believe the 7941 phones are not supported on CUCM 14. Do you mean 7841?

Maren

[chrzan]

Hello,

           We have tried factory reset and changing firmware . Call statistics show no packet loss or jitter. "From Cisco about 7941 The following table lists Cisco endpoints that have reached the End of Support date, but which are not yet deprecated. Unlike deprecated endpoints, you can still deploy these endpoints in the latest release"

If it was a routing issue would'nt it happen to the8811's ?

[Maren Mahoney]

Oh! I inferred that it was both model phones. Sorry. And you are right that the 7941Gs are End of Support but not deprecated in v14.

If the phones are not experiencing jitter and packet loss but are exhibiting the behavior you describe, it is absolutely the phone. You have tried more than one firmware. And it only affects the one model. It would be time for a TAC case, but as you already noted those phones are end of support.

There is a super-old bug (CSCvd30515) affecting 79XX phones where the codecs in the OLC and Start Media Transmission are different that describes the behavior you are experiencing. I'm including the bug so you can read it, but it might be worth checking.

I wish I had a better answer for you.

Maren