CP-8821 Bad Voice Quality and MOS LQK feature

[salvatore.parisi]

Hello,

I have a call quality problem with CISCO CP-8821.

In our Company we have this scenario :

- CUCM Version : 10.5.2.12901-1

- CP-8821 load ID : sip8821.11-0-2SR2-1

- CP-7925 load ID : CP7925G-1.4.8.4.LOADS

The CP-7925 Phones works fine.

The CP-8821 Phones works bad, the most frequent problems are :

- Network busy message (unable to answer or make a call)

- Digital Noise during a call 

- Discontinuous call (silence during a call)

How can I do ?

Furthermore, on CP-8821, I can't read the voice call quality parameters like MOS LQK. The values are always zero (see the attached file)! Why ?

On CP-7925 I can read the parameters (MOS LQK) without any problem.

Thank you,

Salvo

[Manish Gogna]

Hi Salvo,

Regarding the second query please check the following link

http://www.cisco.com/c/en/us/products/collateral/cloud-systems-management/prime-collaboration/white-paper-c11-735409.html

It says " The latest Cisco IP Phones (Cisco DX Series and Cisco IP Phone 7800 and 8800 Series devices) as well as future IP phones no longer report MOS."

The call related issues you mentioned point to some issue with the network , i would recommend verifying the setup as per the wireless IP phones deployment guide. If the issue persists you will need to contact TAC with the running config from access points, captures from AP for a call facing the issue and corresponding cucm callmanager service traces.

HTH

Manish

[salvatore.parisi]

Hi Manish,

I saw few differences beetween the current configuration and the deployment guide.

But the differences are due to the CP-7925 deployment guide settings.

I fear that modifing the WLC configuration (fixing the differences in the deployment guide) I might have problem with CP-7925.

CP-7925 and CP-8821 can works in the same network ?

BR

Salvo

[Manish Gogna]

Hi Salvo,

Yes, they can. You can refer the following doc for some recommendations on such a deployment

http://www.cisco.com/c/en/us/support/docs/collaboration-endpoints/unified-wireless-ip-phone-7925g/200032-How-to-get-your-792x-wireless-phones-per.html

Manish

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[salvatore.parisi]

Hi Manish,

about bad quality on 8821, we did other tests with different devices :

Device A	Device B	Quality
CP 8821 (Wifi LAN)	CP 7841 (Wired LAN)	Bad - Choppy voice only on 7841 side
CP 8821 (Wifi LAN)	CP 6901 (Wired LAN)	Bad - Choppy voice only on 6901 side
CP 8821 (Wifi LAN)	CP 8841 (Wired LAN)	Good
CP 8821 (Wifi LAN)	CP 7925 (Wifi LAN)	Good
CP 8821 (Wifi LAN)	CP 8821 (Wifi LAN)	Good
CP 8821 (Wifi LAN)	External Call (through PSTN)	Good

As you can see, the problem occurs on 7841 and 6901.

Notice that the choppy voice occurs only on 7841 and 6901 side.

I think that this behavior is a Bug.

I Found this : Cisco Bug: CSCvc98741 - Voice quality garbled and choppy 8821<-->7841 some pkts not forwarded to wired side

What do you think about it ? Is There something that we can do ?

Thank you,

Salvo