Comcast assigned every mobile customer the same unchangeable PIN to protect against SIM hijack attacks: 0000

If someone wants to steal your phone number -- say, to intercept the two-factor authentication SMSes needed to break into your bank account or other vital service -- they hijack your SIM by impersonating you to your phone company (or by bribing someone at the company to reassign your phone number to them), and this has made the security of phone numbers into a top concern for security experts and telcoms companies, as there are millions of dollars at stake. Read the rest