There are some hillarious 419eater meet comedy answering apps that direct random pre-recorded skits to the scammer.

When real-time natural speech synthesis arrives with unique accents, coupled to hardware-accelerated machine-learning, it would be within the realm of possible to direct a Turing-test-capable bot to waste a scammer's time with a generated situation and personality that meets various plausibility, social, customer qualifiers and scam-delaying constraints. Also at said point, the "are you a bot?" question non-IRL will be even more worthless but possibly comical.

Except that most telemarketing calls are themselves robots/recordings, so I'm not sure this helps anyone.