[cisco-voip] strange call issue

[Go0se]

We have a customer with CM6 that has a 3725 with 3 PRIs to the same telco.
The cisco users are complaining of issues, such as a "loud squeal" and then
the call drops or also a "robotic sound" and then the call drops. Apparently
the PSTN caller can hear nothing at all. They average about a dozen (+/-)
per day. The T1 controllers are ALWAYS clean, no errors, no slip seconds,
etc. QoS appears correct. The strange part is this: tracking the issue with
the QRT tool the issue always seems to tie to the same PRI - until we reboot
or change something. Originally the issue was on controller 1/1 - for
several days the QRT issues were ALWAYS on the same controller. We upgraded
the IOS and rebooted and it moved to controller 1/2. Thinking it was
possibly a DSP issue TAC shipped out replacement DSPs. We replaced the DSPs
and the issue remained on 1/2. We put controller 1/2 in "shutdown" state and
the issue moved back to controller 1/1. TAC asked us to do a PCM dump but we
made test calls for around an hour and a half - and had one bad test call,
but the call dropped before we could run the dump. 

 

This has been going on for months and we are no closer than when we started.
Any input would be appreciated.

 

Thanks,

 

Go0se

 

My blog: 

 <http://atc.go0se.com/> http://atc.go0se.com

 

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