From Habr.

XXX is my favorite topic. Trolling of spammers.
First, get the habit instead of “allo” to say “washing room”, “synagogue”, or “duty captain Atabayev is listening!”
This sometimes causes a funny pattern break :)
You can still say instead of allo right away: "Good morning, Sergey Petrovich please call!"

A few times in the laundry room they said, “Daaah? “Sorry...” Once there was just a plague dialogue:
I am the synagogue!
Tagged with: allo! Is it an apartment?
I: I tell you, this is a synagogue!
Spammer: Are you an organization?
I: In your opinion, the synagogue is not an organization?
Spammer: (hanging the phone)

Further, if there is no time. Do not turn off, but just put the phone next to the table and continue to do your business. Let it go into the emptiness.

You can listen to a monologue and then say, “I’m sorry, I didn’t listen to you. Please repeat it again :)

And the most vicious and cruel trolling: pretending to be terribly interested in the service offered, but hearing just terribly bad. Speak loudly and ask to repeat. “What is? What is the speed of the internet? The AAAA? Excuse me? Repeat it again! Badly heard! Oh you are!! What a great offer! What? Congratulations again louder! It’s bad!” :D :D But it’s very bad.