I just block all callers except contacts. I mean in this era, communications for me is whitelist only except when I’m expecting a call from a number no in my contacts, then I turn off my call blockers and use the default spam blockers built into samsung (don’t really know how or if it works, but I rarely need to receive a call outside my contacts). So what I do is just pick up a call, say nothing, just listen. If what I hear doesn’t match my expected phone call, I just hang up. Any extra third party anti-spam apps might just falsely mark a phone call as spam, also, letting such apps monitor your phone calls has a privacy issue.

TLDR: Use whitelist only, unless expecting a call, then disable whitelist only mode. Don’t need 3rd party apps for rare occurences.