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New Member

Jitter and Humming Noise when placing calls

Hello Guys,

I'm having a problem with Jitter and humming noise when placing calls. This happens anytime we place an outside call-- I will paste the configuration we currently run in our voice-ports for analysis. This problem seems like its getting worse and worse by day. Please let me know if you all have any solution or recommendations.

Current Voice-Port Configuration--

signal groundStart

input gain 6

output attenuation 0

echo-cancel coverage 16

playout-delay maximum 160

playout-delay nominal 80

playout-delay mode fixed

no comfort-noise

connection plar 7050

music-threshold -45

caller-id enable

Cisco Employee

Re: Jitter and Humming Noise when placing calls

Is there any reason why the gain, attenuation and playout delay buffer are set to non-default values?

Fixed playout delay generally does not work as well as adaptive. Take a look at this page to see how to get jitter stats right off the dsp:

the music-threshold set as it is may present the echo cancellers with a difficult situation as well.

New Member

Re: Jitter and Humming Noise when placing calls

I have tried different configurations, as I start changing the defaults--the problem seems to get worse and worse. Is there a value you recommend for those configurations? Your input would greatly be appreciated.


Eloy Chio


Re: Jitter and Humming Noise when placing calls

You might consider putting a trouble ticket into your local carrier to have them check the quality of your trunk to the PSTN. Maybe something is not up to speed there, and if not at least you can rule that out.