one way jitter and skips

[desrochj1]

hello,

some of my users are experiencing voice skips with their telephone.

it always seems to be one way skips, because the other person

at the other end says voice quality is ok and no skips.

it is strange because those people experiencing voice skips

are in the same building and they never cross wan links.

they are all connected with good 2960 cisco switches, 1gig uplink

per switch, and all to switches goes in the same 3750 stack in the building.

they should have plenty of bandwidth. Voice skips also happen on internal

phone call between the users in the same building.

there is something causing this on the lan.

I don't know where should i start my investigation

i need your suggestions on this

we are using cisco call manager 4.2

most of my ip phones are 7940, 7911, 7942, 7960

thanks

[bryantlowe]

when on a call that is having issues, hit the ?

twice. this will bring up call details. What is the Max Jitter?

[desrochj1]

i do not have access to the phones right now , is there a way i can do this remotely ?

thanks again

[dksingh]

You shd be able to click on phone's IP to get into phone's GUI

and then click on Streaming Stats/Stream 1

Direct URL:

http:///CGI/Java/Serviceability?adapter=device.statistics.streaming.0

[desrochj1]

ok i see the stats on the phone

max jitter is a 2 but there is no voice skips for now...

since there is no voice skips on all answered calls.

it's tough to know when someone has call call that's skips

and get the data in realtime.

what should i check for this kind of problem ?

thanks

[dksingh]

Intermittent voice quality issues could be tough to troubleshoot due

to unpredictable nature of the problem.

Since in your setup, its happenening internally between IP phones

as well, I'd suggest to check the switchport interfaces to make

sure there is nothing going on there. Also try and find out if it has

any relevance to time of day/day of week to see if there is a backup/

cron/data intensive app. flooding the LAN during that window.

Reviewing L2 QoS and IP phone firmware version will be good idea.

Ideally, if we can get a sniffer off the phone with a capture for one

such sample, we can tell a lot but its not always possible to capture one.

Maybe you can hookup a sniffer to a phone that is seeing this more

frequently than others and let it run till the issue occurs?

[Steven Holl]

If you can't collect information in realtime, then configure QRT on this users phone, and have them use the QRT button to report the call as or after it occurs.  You can then look at the call stats post-mortem.  If you see packet loss/jitter, investigate the IP nertwork.  If the stats look okay, at that point a packet capture would be necessary to identify if the issue is in the audio payload.