  We model the mobility of mobile phone users to study the fundamental
spreading patterns characterizing a mobile virus outbreak. We find that while
Bluetooth viruses can reach all susceptible handsets with time, they spread
slowly due to human mobility, offering ample opportunities to deploy antiviral
software. In contrast, viruses utilizing multimedia messaging services could
infect all users in hours, but currently a phase transition on the underlying
call graph limits them to only a small fraction of the susceptible users. These
results explain the lack of a major mobile virus breakout so far and predict
that once a mobile operating system's market share reaches the phase transition
point, viruses will pose a serious threat to mobile communications.
