Users hear a noise, like a machine hum (I verified) on calls via FXO to the PSTN.
I've tried the following on the voice-port
no caller-id enable (a bug a long time age :)
input gain manipulation
output attenuation manipulation
echo-cancel coverage manipulation
I have noted that the Router (2821) is not grounded and am having the customer take care of this. Could this be a possible cause?
Using an analog test set straight into the circuit, I do not hear the noise.
Possible dsp issue? sho dsp error shows no errors.