STIR/SHAKEN requires that calls traveling through US phone networks have their Caller ID number “signed” as legitimate by originating carriers, then validated by recipient carriers as the phone call travels to the target recipient. Using STIR/SHAKEN, we can authenticate each phone call’s origin for each carrier involved in delivering your message. This ensures that your messages make it through more of the increasingly dense layers of SPAM filters implemented by carriers and by individual phone users.