Did something similar when DD was 3. Kept getting telemarketer calls with a 1-800 number and I'd pick up and there would be no-one there. I finally called back and got voicemail. Then I handed the phone to DD. I think it took 3 calls after their voicemail listened to her babel on and on for 30 plus minutes (she is a talker!) and they stopped calling!
Strangest call to date was someone asking if I sold donkeys. After a few questions I let them talk to my 3 yr old who happened to be asking for the phone at just hte right time.
Normally though if I don't have what the person wants, I'll give them a name and number of a person that might have it.
I could use a peacock and peahen breeders name and number.