The advancement of computers has also led to the evolution of telephone technology. From traditional PSTN networks and mobile devices we have moved on to the era of Voice over IP (VoIP) and smartphones. Integration of the Internet into everyday life has led to the demand for web access on-the-go and the widespread adoption of new generation mobile devices. Such Internet-enabled devices are becoming increasingly popular, with smartphone users expected to exceed 1 billion worldwide by 2014. Additionally, VoIP subscribers will reach almost half a billion worldwide by 2012. Thus, one can expect that in the near future, legacy telephony technologies will slowly become obsolete. Nonetheless, in this transitional period where such technologies co-exist, we can expect the emergence of new threats that exploit their interconnection. As demonstrated in our previous work, as well as in the wild, an attacker can leverage VoIP technology to flood traditional telephone devices with a large number of missed calls1 and render them unusable. We demonstrated the feasibility of such an attack, which we refer to as DIAL attacks, by leveraging VoIP technology.