reading the description, it’ll be most effective in the US because of the STIR attestation being one of the criteria. other than that, it’ll probably work as well as the rules you configure.

I get very little spam since I ported my cell number to voip. I figure they have filters in place.

Get a phone number from a area code you don’t know anyone in (montana for example), route all calls from that area code to voice mail, never ring. 99% of spam is solved.