Block or reroute illegal robocalls during call set-up phase.
Our proposed method keeps robocalls from reaching their targets by creating and maintaining a database of blacklisted caller IDs. This requires a central database and authentication system that associates encrypted passwords with each registered ID. Unregistered robocallers are identified by the natural behavior of the targets who answer, plus similarity to previously blacklisted callers. Once on the blacklist, illegal calls may be rerouted, spoofed, or blocked.