Exactly, sometimes these systems are purposely used to deny legitimate users. Sort of like OS account lockouts (too many failed attempts). What if their goal is to lock the users out?
What happens when someone uploads 4 billion IPs
i recon he'll get blocked from contributing to the block-list
There's some room in the missing ~295 million IPs
What happens is that you find out why this is a terrible idea.
And someone gets sued for tortuous interference and defamation.
They'd need to originate SIP traffic from your IP or try to spoof your IP. If they are doing that, they may be targeting different things not SIP related.