The timings between the events (telemarketer calls, victim answer, telemarketer plays automated random greeting, victim replies, telemarketer transfers call to

The timings between the events (telemarketer calls, victim answer, telemarketer plays automated random greeting, victim replies, telemarketer transfers call to human operator, etc.) can be used for an effective blocking. Like a more advanced Lenny, play an audio captcha that an human call would hear but that will also get lost to a telemarketer and, when call arrives to their operator, the victim's system is already playing random funny stuff to burn up their time.