VoIP phones cut in/out - QOS

[afsharki2]

Hello, I have a couple users on a 3850 switch that sometimes randomly are talking to someone and only hear every other word (choppy cutting in/out ). I've replaced the phones (6921), handsets etc.. ethernet cords, switchports etc..  I've also checked the switch and made sure all other IP phones are working well.  I've checked counter errors things like that, but found nothing.

Now I would like to check QOS because every switchport does have  a serivce-policy attached to it. Does anyone know what's the best way to troubleshoot this?   How do I figure out which of the 8 queues voice packets go through? commands would be great.

Please let me know if I'm missing info

Also, can anyone recommend reading an article that explains the 3850 queue structure and how it's built to handle traffic?

Thank you

[Dennis Mink]

Tell us what the voice path is, are you getting choppy voice when you call between 2 phones on the same switch?  is it between switches?  is it calls across the WAN, is it external calls?

Typically, you can use autoQos on your access ports and simply trust the DSCP values that the phone sends, across your switch trunks

Please rate if useful

[afsharki2]

sorry for not putting enough info.  All calls applicable whether they be on the same switch or calling someone with a cell phone. Qos is already configured to trust the dscp values.  trust device cisco-phone command is present on the switchports. 

[paul driver]

Hello
Usually you would trust the voip phone to mark the voice and data traffic and then providing you dont have any latency within your network you shouldn’t get any jitter.

Without seeing you qos setup it hard to tell at this time, But I took the liberty of checking the admin guide for this particular phone ( see attached) an it does  support what I mentioned regards network latenvy and  jitter.

Cisco6921

res
Paul