Instant messaging solved all this shit 700 years ago!
Let each number act as an "account" on the phone network/company, just like IM accounts, each with its list of contacts, and blocked numbers.
Shove incoming calls into "Strangers" with low-annoyance notifications (ringtones) by default unless they're from a "verified" company etc.
Oh and yeah as others said, a "Report Abuse" button.