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

[Asterisk Bug Tracker]

The following issue has been UPDATED. 
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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:                    Asterisk
Issue ID:                   17903
Category:                   General
Reproducibility:            random
Severity:                   major
Priority:                   normal
Status:                     feedback
Asterisk Version:           I did not set the version :( 
JIRA:                        
Regression:                 No 
Reviewboard Link:            
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!):  
Request Review:              
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Date Submitted:             2010-08-23 20:20 CDT
Last Modified:              2010-10-12 23:08 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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---------------------------------------------------------------------- 
 (0127926) sruffell (administrator) - 2010-10-12 23:08
 https://issues.asterisk.org/view.php?id=17903#c127926 
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I'm moving this out of DAHDI-Linux since I'm nearly certain this isn't a
driver problem.  Something in your network is generating fax answer tones,
so either fax detect is setup in an asterisk server, softphones have fax
detect software installed, there is a fax machine monitoring the line,
etc..

Nothing in DAHDI would generate a 2100hz tone that I'm aware of. 

Issue History 
Date Modified    Username       Field                    Change               
====================================================================== 
2010-10-12 23:08 sruffell       Asterisk Version          => I did not set the
version :(
2010-10-12 23:08 sruffell       Regression                => No              
2010-10-12 23:08 sruffell       SVN Branch (only for SVN checkouts, not tarball
releases) => N/A             
2010-10-12 23:08 sruffell       Note Added: 0127926                          
2010-10-12 23:08 sruffell       Category                 dahdi (the module) =>
General
2010-10-12 23:08 sruffell       version                  2.3.0.1 =>          
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