In 2006 WinLock ransomware was unleashed on PC users. WinLock displays pornographic images until victims send a $10 premium-rate SMS to receive an unlock code.
WinLock was spread by another ransomware worm that imitated the Windows Product Activation notice and gave victims an international number to call to input a six-digit code. The call would be rerouted through a country with high international phone rates, and the person would be kept on hold while the fees racked up.
In 2010 ten people responsible for Winlock were arrested in Moscow, the gang had been in operation for about a year, and reportedly earned over $16 million from this SMS scheme.