static issue with VOIP phone


We are using Alcatel OXE systems in our two campuses of our school. We are experincing some random VOIP static issue between two campuses which are connected via 20M IPVPN.

The VOIP "static" issue has been there for quite a long time, preliminary troubleshooting approaches have reached their limits,but we haven't yet found the root cause of this issue.

QoS settings are in place for both ends.

I would like to your help, tips, direction; any info and help would be hihgly apprecioated.

Many thanks in advance.


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jfaubiontxConnect With a Mentor Commented:
Just following up as I had a customer today with static issues. Their rack was grounded to a nearby water pipe and not to their A/C ground. We had a 400+ milliamps of current between the grounds. Moving the rack ground to the common A/C ground bar cleared up the noise.

Were you able to find anything with the grounding?
By static, do you mean crackles like an old vinyl record, noise more like a hum or more like a repeating pattern of clicks or pops? We see the crackle like static like that of dust on an old record in VoIP systems mainly due to connection in the analog paths such as handset cords and such. Most hum comes from grounding issues. Things like the server and/or the phone power supply not having an equal ground. Maybe there is a difference on potential between the two grounds. The last type is typically related to jitter issues. Jitter is often caused by timing of the packets in the path. Using MTR or a series of trace routes can help locate the source of these issues.

Jitter Wiki

Just to be clear, you are not referring to dropped packets right?  e.g. a dropped word or partial word and intermittent....
Static is different from drops
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mbsadmin1Author Commented:
To jfaubiontx:
Thanks for your advice, I am organising electricians to check earth grouding for every switch rack and VoIP equipment in both campuses. I will let you know the outcome when the electricians finish their job.  

To: atrevido:
Static means  --- "static like that of dust on an old record"
mbsadmin1Author Commented:
jfaubiontx: Thanks for the follow up. We are in the process of  doing A/C ground for all racks, switches and servers at moment, an electrician will be brought in to carry out this task, I will let you know the outcomes.



mbsadmin1Author Commented:
We solve this issue by the followings:

1.) earth grounging
2.) Disable STP on Aruba controllers
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