[asterisk-bugs] [DAHDI-linux 0017903]: Screech Sound (loud noise) heard every 100-200 calls in call centre environment

Tue Sep 28 23:34:16 CDT 2010

A NOTE has been added to this issue. 
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https://issues.asterisk.org/view.php?id=17903 
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Reported By:                integratedvoip
Assigned To:                
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Project:                    DAHDI-linux
Issue ID:                   17903
Category:                   dahdi (the module)
Reproducibility:            random
Severity:                   major
Priority:                   normal
Status:                     feedback
JIRA:                        
Reviewboard Link:            
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Date Submitted:             2010-08-23 20:20 CDT
Last Modified:              2010-09-28 23:34 CDT
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Summary:                    Screech Sound (loud noise) heard every 100-200 calls
in call centre environment
Description: 
I have this happening on 3 clients now and it is getting to be a serious
problem.

These machines are connected to existing Phone systems via ISDN to record
calls and to directly connect SIP extensions.

On 2 machines the caller (connected to the existing phone system or via
SIP) hears the screeching sound (or loud noise) and then has to hangup the
call as it does not stop. On 1 machine the callee (on the other end of the
ISDN) hears the  screeching sound (or loud noise) and then has to hangup
the call as it does not stop.

I have the same configuration (i.e. connected to the Teclo and PABX to
record calls) on a number of clients and it works fine with large volumes
of over 20,000 calls per day on the same hardware.

I do not think this is a configuration issue, rather an incompatability
issues with certain PABX systems and we would need to find a workaround for
them.

This is causing me to pull me hair out. If someone can solve this one for
all machines I will make a minimum $500 support payment to the online
community of your choice.
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 (0127489) integratedvoip (reporter) - 2010-09-28 23:34
 https://issues.asterisk.org/view.php?id=17903#c127489 
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I have come to one of the sites today armed with a Sangoma card hoping that
will fix this and it has not fixed it.

The good news is i was able record the offending audio for the first
time.

I accidently had faxdetect turned on and there were messages in the logs
saying:
Sep 29 12:35:44 jamieson dahdi: Disabled echo canceller NLP because of CED
tx detected on channel 62
Sep 29 12:35:44 jamieson dahdi: Disabled echo canceller NLP because of CED
rx detected on channel 1
Sep 29 12:38:52 jamieson dahdi: Disabled echo canceller NLP because of CED
rx detected on channel 2
Sep 29 12:38:52 jamieson dahdi: Disabled echo canceller NLP because of CED
tx detected on channel 61
Sep 29 12:54:59 jamieson dahdi: Disabled echo canceller NLP because of CED
rx detected on channel 32
Sep 29 12:55:39 jamieson dahdi: Disabled echo canceller NLP because of CED
rx detected on channel 32
Sep 29 12:56:19 jamieson dahdi: Disabled echo canceller NLP because of CED
rx detected on channel 32
Sep 29 12:56:53 jamieson dahdi: Disabled echo canceller NLP because of CED
rx detected on channel 4
Sep 29 12:56:53 jamieson dahdi: Disabled echo canceller NLP because of CED
tx detected on channel 59
Sep 29 13:25:18 jamieson dahdi: Disabled echo canceller NLP because of CED
rx detected on channel 32
Sep 29 13:45:46 jamieson dahdi: Disabled echo canceller NLP because of CED
rx detected on channel 1
Sep 29 13:45:46 jamieson dahdi: Disabled echo canceller NLP because of CED
tx detected on channel 59
Sep 29 13:48:51 jamieson dahdi: Disabled echo canceller NLP because of CED
rx detected on channel 10
Sep 29 13:48:51 jamieson dahdi: Disabled echo canceller NLP because of CED
tx detected on channel 54
Sep 29 13:49:41 jamieson dahdi: Disabled echo canceller NLP because of CED
rx detected on channel 9
Sep 29 13:49:41 jamieson dahdi: Disabled echo canceller NLP because of CED
tx detected on channel 55
Sep 29 13:50:12 jamieson dahdi: Disabled echo canceller NLP because of CED
rx detected on channel 7
Sep 29 13:50:12 jamieson dahdi: Disabled echo canceller NLP because of CED
tx detected on channel 58
Sep 29 13:51:48 jamieson dahdi: Disabled echo canceller NLP because of CED
rx detected on channel 4
Sep 29 13:51:48 jamieson dahdi: Disabled echo canceller NLP because of CED
tx detected on channel 53
Sep 29 13:56:33 jamieson dahdi: Disabled echo canceller NLP because of CED
rx detected on channel 12
Sep 29 13:56:33 jamieson dahdi: Disabled echo canceller NLP because of CED
tx detected on channel 52
Sep 29 14:19:04 jamieson dahdi: Disabled echo canceller NLP because of CED
rx detected on channel 3
Sep 29 14:19:04 jamieson dahdi: Disabled echo canceller NLP because of CED
tx detected on channel 62
Sep 29 14:22:37 jamieson dahdi: Disabled echo canceller NLP because of CED
rx detected on channel 11
Sep 29 14:22:37 jamieson dahdi: Disabled echo canceller NLP because of CED
tx detected on channel 55
Sep 29 14:24:36 jamieson dahdi: Disabled echo canceller NLP because of CED
rx detected on channel 13
Sep 29 14:24:36 jamieson dahdi: Disabled echo canceller NLP because of CED
tx detected on channel 53

These error messages may simply be because asterisk has detected the noise
as an fax signal.

Audio file attached. 

Issue History 
Date Modified    Username       Field                    Change               
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2010-09-28 23:34 integratedvoip Note Added: 0127489                          
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