I asked Bing GPT4 how I can do that on iPhone. Here is the answer :

There are some apps and services that claim to use AI to answer telemarketers calls on your iPhone. One of them is Jolly Roger Telephone, which uses ChatGPT and voice cloning to create and read scripts to telemarketers, acting as digital, fictitious characters that keep scammers on the line¹². You can subscribe to this service for $24.99 a year and access the accompanying apps to view, listen, and share recorded calls between the bot and the frustrated telemarketer¹. Another app is Call Control, which features smart block technology to automatically block calls from millions of spammers, telemarketers and robocallers³. You can download this app for free from the App Store³. I hope this helps you deal with pesky telemarketers.😉

Anyone tried ?