I'm sharing again my tip against robocallers and telemarketers, because I just used it successfully again.
From what I understand, at least where I'm living, those systems work in the following way:
- An automated system calls a number from a database
- If the call is answered, it tries to detect who or what is answering: a person? A voicemail or other machine? For old landlines, a fax or modem?
- If it's person, transfer to a human operator. Otherwise, hang up.
So here is my strategy : if you get a call from an unknown and possibly dubious number, take the call and then remain absolutely silent. If it's a real person, they will end up speaking. If it's a call center, the system will just wait for you to speak and, after a few seconds where you don't, end the call by itself. Without any interaction with a telemarketer.