To clear this up, I do not have my cell number on facebook either. Turns out, when trying to post a picture from my mobile, I could either sign into facebook with my username OR my telephone number. It just was not clear when the login page came up. In fact when I tried to register my cell phone number on facebook they emailed back and said that the carrier (verizon) did not recognize my number. I keep getting emails to that effect. I just let the issue die and log in with my user name.