I got this weird looking message on my iPhone today. Black screen, only displaying the message, and only has a green dismiss button at the bottom. Looks like a carrier alert, but clearly a spam message. To see what it looks like, image search for iphone flash sms.
It turns out, there’s a class of SMS called “flash SMS”, usually used by carriers, but some phones can send them, and the stupid thing about iPhone is it doesn’t display the sender, so people think it’s an official message. Good thing mine was clearly spam, so I ignored it. If it said “press Dismiss to reset to factory settings”, I might have been fooled.
So if you get a message like this, you know what it is!