I've recieved a lot of forex related telemarketing calls the past two years (not robo, but imagine it will also hit EU eventually) because I was silly enough to input my actual number at some platform 5+ years back. I've tried several approaches reasoning with those individuals, mostly using the logic that I will NEVER buy anything from them because im simply not interested in the topic, but also a few using foul language. Always same result: more bullshit politely accompanied by "sir".

More recently I've recieved a lot of calls from regular people "calling me back". I reached out to my provider a few times, especially about the spoofing, but they claim theres nothing they can do, which I highly doubt.

I was a bit inspired by Cory Doctorow's "Red team blues" wherein the protagonist carries a burner, but has her main number behind an Asterisk server forwarding allowlisted numbers to the active burner.

Anyone know of anything like this? Ideally very DIY and FLOSS?

I imagine you could do some cool stuff with Whisper and LLMs, either wasting their time (like lennytroll mentioned elsewhere), but even better some autonomous bastion asking the caller to explain their reason for calling and letting the owner validate the answer through speech-to-text in an app, then decide wether to let it through or to "let me tell you in great detail about my grandchilds vacation to Mauritius"-land.

It's a weird opposite world we live in where companies hide behind endless teleprompts, but citizens have no such shield