Protecting Against Caller ID Spoofing Attacks Using In-band Signaling

Whenever one receives a phone call, the Caller ID is the first bit of information that is being processed. Based on this information, one may choose to accept the incoming call or to reject it. Furthermore, the Caller ID is the element that sets the trust premise of the call, even before the actual conversation begins. Unfortunately, the value of the Caller ID is neither guaranteed in any way by the telecommunications company nor is it imposed and can easily be spoofed by a malicious actor in order to start an attack that wouldn’t be possible otherwise. This paper presents a method of identifying a spoofed Caller ID, method that is applicable to smartphones with no need of additional hardware, no additional running costs or the implication of third-party entities.