Mobile networks are vulnerable to signalling attacks and storms caused by traffic that overloads the control plane through excessive signalling, which can be introduced via malware and mobile botnets. With the advent of machine-to-machine (M2M) communications over mobile networks, the potential for signalling storms increases due to the normally periodic nature of M2M traffic and the sheer number of communicating nodes. Several mobile network operators have also experienced signalling storms due to poorly designed applications that result in service outage. The radio resource control (RRC) protocol is particularly susceptible to such attacks, motivating this work within the EU FP7 NEMESYS project which presents simulations that clarify the temporal dynamics of user behavior and signalling, allowing us to suggest how such attacks can be detected and mitigated.