There have been vulnerabilities related to tel: URIs before, in particular this one that let you factory reset Samsung phones. http://www.techhive.com/article/

There have been vulnerabilities related to tel: URIs before, in particular this one that let you factory reset Samsung phones. http://www.techhive.com/article/2010562/reported-android-flaw-could-wipe-your-samsung-galaxy-s-iii.html http://www.techhive.com/article/2010562/reported-android-fla...