Trailrunner7 writes, quoting Threat Post "By tweaking the firmware on certain kinds of phones, a hacker could make it so other phones in the area are unable to receive incoming calls or SMS messages, according to research presented at the USENIX Security Symposium. The hack involves modifying the baseband processor on some Motorola phones and tricking some older 2G GSM networks into not delivering calls and messages. By 'watching' the messages sent from phone towers and not delivering them to users, the hack could effectively shut down some small localized mobile networks. Essentially the hacked firmware ... can block ... pages by responding to them before the phones that were initially intended to receive them do, something Kevin Redon and company called during their research 'the race for the fastest paging response time.'" Thanks to the power of Osmocom BB, which has implemented Free Software baseband for several GSM devices. Also see the research paper.