Packet loss query - Intermittent calls whereby other party can not hear person

[armstr_a]

Hi,

We have an issue with our Mitel3300 whereby users are having issues whereby the other end cannot hear the person talking at times. This is both incoming and outgoing intermittently. Our ISDN30's have been checked and come back as all clear and working fine.
Our phone support provider has checked the Mitel logs and stated it is a IP issue not a digital and believes its traffic on the LAN that is causing this likely.

Our IT provider however are saying they cannot see anything un-ordinary on the switches and pushing me back to mitel.

On the maintenance logs i am seeing quite a few of these -

E2tSp
Description  IP Network Dropped 2.84 percent of Packets from phone 192.168.0.119 Total Rx: 308 Lost=9 maxLossBurst=1 1 in a row: 9 2 in a row: 0 3-5 in a row: 0 6-10 in a row: 0 11 or more: 0

Also under voice quality statistics the Jitter buffer avg. depth has values against it for each phone some are 0 but some are as high as 39?

Does this point to a local lan issue causing this? anyone experienced this before or could advise what i can check?

thanks in advance

[x-man]

My initial reaction would be that its your network. To be sure you would have to run a BERT test on the isdn 30 from your end though. Has this been done. Do you get packet loss on internal calls?(i.e is the problem JUST on external calls?).

Have you got QoS enabled on the internal network?

Have you seen this? http://173.239.188.38/uwi/help/En/sysadmin/pdfs/mivoice_business_7.2_vqtrbl.pdf (basics are same for most releases).

[VinceWhirlwind]

"Total Rx: 308 Lost=9 maxLossBurst=1 1 in a row: 9 "
 
This tells you it's the very occasional packet going missing and probably *just* enough for a caller to notice sub-optimal voice quality, but not enough for them to report "can't hear the other person" (for this call anyway). You probably want to observe the stats for a call that has been complained about.
 
From this, I would assume the network was (mostly) sound, but that there is congestion occurring somewhere.
As advised above, you should first figure out whether it's the same for internal and external calls - this might help you narrow down the controller/server/switch or router interface where the intermittent congestion is occurring.
And ultimately, this is quite possibly an issue you could solve by ensuring you have either QoS or traffic-shaping configured on the relevant device.