Voice over IP Cisco - Echo and Static on IP to IP Phone Calls

Author

Echo and Static on IP to IP Phone Calls

tennille.spence@gsa.gov

2005-10-24, 9:12 am

One of our offices started experiencing static on calls last week. When any
calls are sent / received in that office, one of the associates hears
static and echo when speaking into the receiver while the other hears
everything clearly and does not hear any static. A bathroom renovation is
taking place nearly below the office; however, I waited until the workers
took a break and placed a few test calls and still received the line static
with echo. The echo and static occurred only when I was speaking. The
associates have indicated that the problem is intermittent and does not
occur when they are placing calls outside of the building. Any ideas on
what the cause could be?

Tennille Spence
IT Business Liaison
PBS Technology Branch
816-823-1357 Office
816-806-6342 Cell
816-823-5526 Fax

"What lies behind us and what lies before us are tiny matters compared to
what lies within us." - Ralph Waldo Emerson

"Opportunity is missed by most people because it is dressed in overalls and
looks like work." - Thomas A. Edison

Lawrence E. Bakst

2005-10-24, 9:13 am

Assuming you are 10% sure it's IP all the way and there are no analog segments true static has to becoming from the station set after the digital signals are converted to analog. The way that noise gets into the analog section is via the power supply or g
round plane. The source of the noise can come from any of 3 places:
1. phone power via adapter or POE
2. maybe noise on the Ethernet wiring that is getting coupled into the DC power supply inside the phone and then into the analog circuit
3. maybe RF noise

How are the phones powered via POE or AC adapter? If adapter I would look to get the phone(s) on a different AC circuit. You can run a long extension cord for that. Or even better, plug it into a small UPS and pull the plug on the UPS and then you will be
getting power from the battery.

If POE, try changing the port and then try a new wire. You can use a 50 or 100 ft patch cable if you have to.

To check for RF noise get a cheap AM battery powered radio, what they used to call a "transistor radio". The cheaper the better. Turn it on and tune it between channels so you hear static at home and listen to get a baseline. Turn it on at work see if you
can hear RF noise. You can walk around with the radio and use it as a crude RF noise detector. The noise should be less where people aren't hearing static. Walk downstairs and see if it gets worse. As a kid I could always here my mothers vacuum cleaner o
n my radio.

Best,

leb

At 10:57 AM -0500 10/18/05, tennille.spence@gsa.gov wrote:
>One of our offices started experiencing static on calls last week. When any
>calls are sent / received in that office, one of the associates hears
>static and echo when speaking into the receiver while the other hears
>everything clearly and does not hear any static. A bathroom renovation is
>taking place nearly below the office; however, I waited until the workers
>took a break and placed a few test calls and still received the line static
>with echo. The echo and static occurred only when I was speaking. The
>associates have indicated that the problem is intermittent and does not
>occur when they are placing calls outside of the building. Any ideas on
>what the cause could be?
>
>Tennille Spence
>IT Business Liaison
>PBS Technology Branch
>816-823-1357 Office
>816-806-6342 Cell
>816-823-5526 Fax
>
>"What lies behind us and what lies before us are tiny matters compared to
>what lies within us." - Ralph Waldo Emerson
>
>"Opportunity is missed by most people because it is dressed in overalls and
>looks like work." - Thomas A. Edison
>
>
> ________________________________________
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>cisco-voip@puck.nether.net
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