There have been many times I look on Facebook and see people saying, "Don't post your number on Facebook. It's dangerous." Yet I do not see any reasoning behind this. The reason you have a phone number is so that people can get in touch with you. You do not just get a phone so that you can look at it and take pictures and update your Facebook status on the go. You have it to talk to people and, if you have a cell phone, to text someone back and forth. Telephones were the original social network.¹

People that have the permissions to view your cell phone number on Facebook are your friends, in fact that is what Facebook calls said people. You ought to trust them enough to allow them to see your number. If not, then maybe y'all shouldn't be friends on Facebook. I mean, not only can they get your phone number, they can also get your email address, your Yahoo!, GTalk, Skype, etc. names, your birthday, whether or not you're in a relationship, your hometown, and, heck, even know what school you attend and when you graduate said school.

Is having your phone number on Facebook, a number they can find from a number of other different ways, such a bad thing to include on your profile?

Please don't hesitate to correct me on anything in here. I would not mind being proven wrong.

¹ One could argue that before telephones there were fancy dress parties. But, that's another whole book.