Recently one of our extensions gets mass incoming calls supposedly from “100” (nonexistent extension). Those calls are not logged in the CDR nor can I identify the source ip, so I can’t block it and it is rather annoying. Anonymous SIP calls and guest calls are blocked.
Presumably the calls are direct to the phone without Asterisk being involved, so use a firewall well written or easier, just don’t accept SIP requests on port 5060.