What is the advantage if I enable ‘Use alternate anonymous address’ under ‘SIP Privacy options’?
The option will apply only for a private call, which means calling presentation = restricted (0x1) in the ISDN SETUP message.
With the option, it is just putting the host part with “anonymous.invalid” instead of a normal IP address. So it doesn’t change anything for the user (number) part:
The “from” URI will be altered to sip:anonymous@anonymous.invalid instead of sip:anonymous@[gateway IP.