SS7 is broken beyond repair, infact it being a walled garden is the only security it ever had.<p>This ccc talk is a good intro - <a href="https:&#x2F;&#x2F;media.ccc.de&#x2F;v&#x2F;31c3_-_6122_-_en_-_saal_1_-_201412271830_-_mobile_self-defense_-_karsten_nohl" rel="nofollow">https:&#x2F;&#x2F;media.ccc.de&#x2F;v&#x2F;31c3_-_6122_-_en_-_saal_1_-_201412271...</a>