Spam phone calls are a source of user unhappiness, and a tool for unscrupulous operators to prey on vulnerable individuals. Spam callers use increasingly sophisticated methods, e.g., disguising a call with a fake caller-id, such that a receiver of the call is given an impression that someone from their contact list is calling. Robocalls, wherein an automated program originates phone calls that targets individuals, e.g., for unsolicited sales or other purposes are a source of annoyance for phone users. One approach to eliminate such calls is to require authentication by a call originating party. However, spam or robocallers are unlikely to identify themselves as such.
Techniques described herein utilize signaling messages of a phone call to serve as a signature or fingerprint for the phone call. Legitimate phone calls have distinct signatures, while spam-calls, robocalls, and calls with fake caller-id have their own distinct pattern. This difference is leveraged to detect and thwart unwanted calls.
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Liu, Junda; Kalla, Naveen; and Lu, Shi, "Robocall and fake caller-id detection", Technical Disclosure Commons, (December 01, 2017)