One of my favourite things to do when I get a message from a stranger, or I am encountering someone’s phone number for the first time, is to type it into the Facebook Search box.
More often than not, Facebook will tell you to whom the number belongs.
I am sure Facebook sees this as a feature, not a bug, but too me it feels dirty and almost like a privilege escalation where you can supply Facebook with a small amount of data and use it to leverage Facebook into revealing more information about the person.
Of course, this can be disabled in a person’s Facebook privacy settings, but the beauty of the ‘tyranny of the default’, is that people never do, leaving them exposed.
My thoughts : If a user is shocked by a functionality like this, then it should not be enabled by default.
I feel many users would be surprised to think that people might be able to determine their name from their phone number so I don’t think Facebook should be facilitating this.
A better solution would be to move this feature to a ‘Find Friends’ section of their website and require at least a first name or other piece of identifying information before revealing the person’s Facebook profile.
I think this case is analogous to a street address – having the address alone should not allow me to learn who lives at the property – likewise a phone number alone should not reveal a person’s name.