I just got a call on my dorm phone...someone asking for Alex Somebody. I said there wasn't an Alex Somebody living here, and wouldn't you like to tell me what number you called? They repeated the number to me (suckers!), and I informed them that there isn't an Alex Somebody at this number, so they said they'd update their database.
I now know the crucial last four digits of my phone number -- it's 5954. Thank you, telemarketers!