Have you tried searching for Facebook profiles by phone number? Enter one that you know is in a profile or posted to a Wall — even a profile set to private — and let me know what you find.
I have my phone number in my About section and the Facebook search engine returns just my profile, so you know that’s the right one.
But here’s a search I did by telephone number for someone I’m not connected to and who doesn’t have their phone number in their public profile. (Sorry for the blurring — to protect the innocent victim of my research.)