Line Squeal

[motomnt]

I have a 911 center that as soon as they pick up the phone on the admin line they get a 1 to 2 sec squeal. They are currently using POTS lines. We are figuring the voltage coming in on the line is to hot and when the customer goes off-hook it is shorting and causing the squeal. We have done the following tests on the phone lines.
- AC Ring Voltage is 105VAC
- AC Volts on TIP to GND and RGN to GND, ranging from 1.1 to 1.4 VAC
The phone line provider CO is across the street from the customer.
The only thing we were able to get from the provider is that they moved the lines from 100 pair to a different 100 pair where the old 911 lines were on. We even ran wire shark which pointed the squeal is happening before entering the phone system. Look for any guidance eon this issue.Here is the rewritten version of your message:

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I have a 911 center experiencing a 1 to 2-second squeal as soon as they pick up the phone on the admin line. They are currently using POTS lines. We suspect the issue may be due to excessively high voltage on the line, causing a short and resulting in the squeal when the phone goes off-hook. The following tests were conducted on the phone lines:

- AC Ring Voltage is 105VAC
- AC Voltage on TIP to GND and RING to GND, ranging from 1.1 to 1.4 VAC

The central office (CO) of the phone line provider is located across the street from the customer. The provider mentioned they moved the lines from one set of 100 pairs to another set where the old 911 lines were. We also ran Wireshark, which indicated the squeal is occurring before entering the phone system.

Any guidance on this issue would be greatly appreciated.

Here is a link to the squeal.

 

[Westi]

Do you get the same squeal when you use your butt set?
if not then it is the phone system having issues.

Can your phone system adjust the line impedance?

I have done some devices in the past to lower the line voltage by adding 600 Ohm 1/4W resistors into the line. always in pairs one on tip and one on ring to not make things worse and then added more and more resistors until the problems were gone.

Take your multimeter and set it to Ampere measurements and simply go Tip and Ring and see how many mA you get on that. I usually look for not more than 26mA but that is more a gut and experience thing than a real scientific reason.

Joe
FHandw, ACSS, ACIS

https://www.millsidetc.com/

 

[kwing112000]

Take a look at this site.

https://www.sandman.com/products

they have some adapters that may be able to help you.

Kevin Wing
ACSS Small and Medium Enterprise (SME) Communications
ACS- Implement IP Office
ACA- Implement IP Office
Vive Communications

 

[curlycord]

Is the issue on 1 line or all lines?

To me that sounds like a ring (pulsating) followed by the Caller ID signal (short squeal) which is normally sent between the 1st & 2nd ring.

Sounds like a C.O. issue....maybe cross-talk of sorts?

=----(((((((((()----=

http://www.curlycord.com

Toronto, Canada

Add me to LinkedIN

 

[Westi]

@curlycord
I had recently a customer that had this on their first line and measuring all 4 lines they had very different values.
Line 1 had 63mA while the other ones were between 24ma and 26 mA

the provider (Bell Canada) had some sort of special setup done on their main line because they had issues with the old line and "repaired" it which caused me the headaches. They sent out 3 different techs and they all claimed that the line was OK and within their specs. Just to mention none of them were 30 yet so young guns with not a lot of experience.



Joe
FHandw, ACSS, ACIS

https://www.millsidetc.com/

 

[curlycord]

Specs, but they they never say if they at least "heard" it.
Good tips mentioned, thanks.

I reread the 1st post...my eyes didn't pay attention, it's the second squeal we are talking about that I also did not hear the first time.
The first "deliverance" took my attention away from the second.

"We even ran wire shark which pointed the squeal is happening before entering the phone system"

"Do you get the same squeal when you use your butt set?"

I would only add, if not done, is to 1st disconnect the line from the unknown phone system then butt set/wire shark it.

Are these "ground start" lines?

=----(((((((((()----=

http://www.curlycord.com

Toronto, Canada

Add me to LinkedIN

 

[motomnt]

The first sounds you hear are the Ali, ANI, and caller ID. The squeal happens as soon as the phone goes off-hook. Here's what we have done so far:

1. Relocated the lines to a different gateway.
2. Added 600-ohm resistors.
3. Swapped out gateways three times.
4. Added attenuators to the lines.
5. Ran Wireshark and determined the squeal is happening before the phone system.

All of this is captured on the recorder, which is positioned before the phone system. Big V measured the lines after us and informed us they switched from one demarc to an older demarc. Big V claims it isn’t their problem, but the issue follows the line every time. The customer has gone through three different equipment upgrades, and the problem persists. They are currently using the VESTA system for admin lines.