My FreePBX / Asterisk configuration was recently forced into allowing both anonymous inbound calls and SIP guests. So of course we're now getting blasted with spam/hack attempts.
They show up in the log as:
[2020-05-02 11:09:53] WARNING[30801]: res_pjsip_registrar.c:1051 registrar_on_rx_request: Endpoint 'anonymous' has no configured AORs
And we get dozens per second.
Can I make a configuration change to essentially block each of these by some mechanism that just makes the caller wait some huge time (like an hour), then hangs up? I think that would tie up the spammers' resources, and slow the bandwidth they're drawing by orders of magnitude.
So first, is this possible? How do you do it securely?
Second, are there serious downsides to this? E.g., slowing down any configuration reload by an order of magnitude or some such.
Any related thoughts or advice?