Modem pool is a device equipped with multiple SIM cards slots. It can be misused for credit fraud

sending spam or making harassing phone calls. This paper proposed a method based on topic model to discover modem pool behaviors from other communications effectively. Specifi cally

computing the co-occurrence probability of several words is mapped into computing the co-occurrence probability of several SIM cards. The experiments showed that the method can capture the behaviors of modem pool effectively. Combining with features other than behavioral features

the algorithm can discover modem pool misuse behavior accurately.