the analog phone is connected to a Sipura 2000
the sipura uses sip to talk to an asterisk box.
The connection was fine, then all of a sudden, a huge hum came on the line
I rebooted everything, this didnt help.
I changed FXS Port Polarity Configuration
Idle Polarity: and Caller Conn Polarity and Callee Conn Polarity:
from Forward to Reverse and this fixed the problem so far...but i have no idea why ?
Can anyone explain if this could actually fix the hum or maybe it was a coincindence and explain how if you know.
Thanks