Computers do not have a built-in billing system. Phones do: it's called the phone bill. We have already seen the first examples of money-making malware that infects various types of smartphones. This talk will go into details of the currently known smartphone trojans that either place calls or send text messages to expensive premium-rate numbers. How does this work technically? Which platforms are at risk? What kind of premium-rate numbers are the criminals using? How do they route the money back to them without getting caught? And what can we do about this before it gets worse?