Don't bother. They change their number about every week. Blogs say it's Fraternal Order of Police looking for donations but don't believe it - otherwise they wouldn't need to keep changing their number. Be suspicious of everyone who calls these days!
If an "outbound telemarketing call center" is making these calls, they might have hundreds of numbers they can call with. Since those numbers are not public information, it's impossible to block them all in advance.
And of course, scammers might spoof a call center's numbers too, or any number. Or use a burner phone.