Reports are abuzz in the virtual world that the iPhone’s text-messaging system has a dangerous flaw that hackers could exploit to take control of your phone. So if you get a text message with a 'single square character', turn off your phone right away as it could mean someone’s already trying to take advantage of the bug.
Someone could pretty quickly take over every iPhone in the world with this. The bug could let the hacker control all the phone’s functions, including making phone calls and sending texts to other phones.
Windows Mobile contains an analogous flaw and both Google’s Android phone and the iPhone had bugs that would allow hackers to disable their network connections—though Google has patched the problem.