High Jitter Buffer underflow

[plee61]

Hi,
Our call centre agents are experiencing quite a lot of dropped out.
Having a look the controller, the Voice Quality Statistics shows high Jitter Buffer Under Flow (over 2 thousands) for most records.
All the agents' phones are connected to Mitel Border Gateway. I have restarted MBG but in vain.
I have set Qos and DSCP on the switches. What else can I do to diagnose and fix the problem?

Cheers

[ralph]

If you're going across the public internet you loose all QOS.
Lets start 1st with your WAN pipe.   How big is it and what type is it?
A DSL will not provide the same up link speed as a the down link. 
What other type of traffic is hitting the external firewall interface?

I've seen one instance where the carrier showed me a report that showed the customers WAN interface completely saturated between 8 and 5 then it dropped to nothing.   Turns out that half the people in the building was using Pandora throughout the day completely overwhelming the pipe.

Ralph

[plee61]

I have been monitoring the statistic over 2 weeks, the values for jitter buffer underflow is still high (>1000).
the Mitel Cx controller is hosted in the same building as the call centre.
The WAN link is 10mbits/s, the service provider has checked the traffic is fine.

what other things i can look for packets delayed.
I have used wireshark to trace traffic of a phone, which goes to the MBG (mitel border gateway).
So I got a list of UDP packets, and no hint if there is any delay as they are not sequenced.

anyone had jitter problem with VoIP?

[martyn]

Not providing a solution, but have you run the TNA tool from the call centre to see what the call quality looks like? Might give you a lead on where the cause may be.

[plee61]

what is TNA tool, and where do you find it please?

[ralph]

TNA is a software tool that comes with your MBG server.
In the teleworker blade under diagnostics (I believe) you'll find the download link.
Run it on a PC at the remote location.

Ralph