File a police complaint for stalking, intimidation, hate crimes, whatever you want to lump in there. If you do end up trying to escalate this to building management or the telephone company, a police report will light some fires under some asses.

Best case scenario the cops figure out who the number belongs to and pays them a visit. Worst case, you can have an official record of this if you get into a fight with this guy or something.

ACAB and all that but I figure in situations like this it’s a lesser evil to point cops at horrible racists so they have less idle time to fuck with innocent people.