why is it that facebook?

[Janet]

insists on you giving them your private cell phone number,when opening an account? i was told by many ppl not just family,but others,that the internet harbors a lot of not so nice ppl ,they could gain access to your address ,get your ip and commit a few crimes like rape and murder.is this a nessecity?my ex friend has bi polarism,hes a mental case,i had an argument with him 6 months ago,hes called me tonight ,,yelled in the phone and hung up.i fear that someday someone will do a number on me,or some other poor unexpecting woman.