Vulgar voice mall from telemarketer...?

Phone companies are always calling trying to sell something...my husband got a call and told the person they weren't interested and hung up. The person called back and said some racist things, swearing loudly the whole time. Our call display says unavailable number so we can't call back or verify it was actually the phone company. We're very upset about this and want to take some action. Has anyone ever experienced this? What avenues can we take? Is it worth it to go to a lawyer? I called the police and they said I would have to fill a report but would need a court order to get the unavailable number unblocked. I'm stunned and don't want people to get away with this kind of behavior....any advice would be appreciated.