MSO QLK count is different at Cisco 7940/7942 phone

[Nikolay Kozyrev]

Hello, gents.

I need you help and advise

I've got a CUCM 7.1.5 + a inbound call from PSTN to my Cisco 7940 phone.

Goes to Status-Network Statistics  ( of double click at " ? " button) I've seen a MOS LQK count = 2. When I transfer this call to the Cisco 7942 the MSQ LQK count = 4.5. Transfer back to Cisco 7940 again have a count = 2.

All phones worked with a SCCP and MSQ ver 0.95  + the same codec g729.

Default CUCM software :

Cisco 7940   SCCP   P003080200

Cisco 7942   SCCP   SCCP42.9-1-1SR1S

As ar as I know  MOS-LQK metrics—Use a numeric score to estimate the relative voice listening quality. The Cisco Unified IP Phone calculates the mean opinion score (MOS) for listening quality (LQK) based audible concealment events due to frame loss in the preceding 8 seconds, and includes perceptual weighting factors such as codec type and frame size.

Any Ideas ?  Why the MSO is diferent in the same callflow at 7940 -7942 ?

[Gordon Ross]

Without knowing if there's a specific bug in the MSO calculations on the phones, I'd start by wiresharking both phones and seeing if there really is a difference in the packets on the wire.

GTG

[Nikolay Kozyrev]

Hello, Gordon.

Do you mean to use a utils network capture file count 100000 size all host   command ?

[Gordon Ross]

That might not work - it depends on the RTP flow. (e.g. using MTPs, etc) Also, I don't trust a device involved in a network conversation to accurately capture the traffic. (Yes, I'm looking at you ASAs !!!)

I always prefer to capture the traffic from outside the device. So I'd port mirror the phone (port span in Cisco speak) and capture the traffic that way.

GTG

[Nikolay Kozyrev]

I see. To create a SPAN port and captured a trafic for analize.

Thanks for advise. I will try

[paolo bevilacqua]

Beside whatever call quality the phone indicates, is there an actual issue in quality, are users complaining?

Because if there isn't, you may end up chasing a cosmetic, non-service affecting issue.