[cisco-voip] Voice Quality After new UPS installed

[su1droot]

Hello everyone,
I have a customer having a problem since they installed a new new
Liebert room UPS.  Since they turned on this new UPS users on ip
phones have been having an intermittent array of problems ranging from
low volume to high volume calls, to jitter.  This happens on ip phone
to ip phone calls, ip phone to voice gateway (3745) calls, but NOT on
voice messages in Unity.  It has been noted that the dial tone on the
phones will sound "noisy."

They have 2 4506 switches serviced by this UPS they are in 2 different
areas be exhibit the same symptoms.  We have run a test where they
took a phone and hooked it up to a hub using a power brick to provide
power to the phone and the problems appear to have gone away.  I am
unable to find an errors and visible problems on the phones or the
switches.  I have looked through the counters on the Ethernet ports
and there are no errors.  no reported power problems on the switches.

Does anyone have any other ideas?  The UPS guys don't' see any
problems with the power that is being output.