[escherplex]

A smart phone app which behaves as a firewall requiring callers to enter, say, a three character PIN code before phone rings may be useful. Incorporate two message files, one for leaving messages from those who know the PIN code and one those who don't, would allow for any contingencies. A front end answering machine box for the home with the same functionalities may be useful as well.

[Loughla]

So shift the burden of calling to literally everyone who is acting well? Why would I want to remember a unique PIN for everyone I know?

Also, isn't that just taking the 9 digit phone number and turning it into a 12 digit?

[escherplex]

Bad actors exist and they're cleaver. Plus these days you don't have to remember anything. Adding an updatable PIN field to a personal call file in such an app coupled with a software protocol with a pop-up button labeled say 'PIN entry' which appears once a contact device answers (say, with a message enter PIN) that can transmit the PIN number would be sufficiently user-friendly for such an app. Better than receiving junk calls while waiting indefinitely for regulations with teeth from dysfunctional legislatures.

[penagwin]

Plus how would we share this "pin"? Maybe we could append it to the phone number, like "+1 (616) 281 - 2123#32343" - Oh wait, it's already a number, what's the point of adding more onto it? It would literally turn into the same system that we have, as you have to share the pin with everyone anyway.

[Evidlo]

It's different because then not every "number" will result in a call being placed. Determining whether a number is valid requires making a call, which ties up robocallers.

[cabalamat]

You could have a Captcha to force that the person on the calling ewnd is a person and not a computer. That would increase the costs for telemarketeers.

Or the system could ask for information that someone who knows the recipient might know but a telemarketeer might not know, e.g. "What is the 2nd letter of my first name?"

[pavel_lishin]

That still shifts the burden onto everyone else.

[Evidlo]

What if the caller was required to know the first character of the recipients last name and enter that on the keypad?

[colejohnson66]

From my experience with robocallers: they already know your name

[howard941]

I bought a Tel-Lynx (this thing http://tel-lynx.com/ ) and it worked great for the paired cellphones and the landline, sort of an automated mini PBX. First time callers had to introduce themselves to the system, spammers never bothered. I'd still be using it if it wasn't incompatible with "flashing" through call waiting calls -- like the phone company it wanted to do out of band signalling with the "flash"

[knicholes]

Is there a way to access the call before it hits your phone? I looked briefly, because I'm very passionate about this problem, and couldn't find anything. I don't want to answer the call and wait for someone to enter a pin. I want them to have entered a sufficiently long randomly generated number (spoken to them by some voice generation service) before it even makes my phone send a notification to me.

[Evidlo]

You might be able to host an instance of Asterisk [0] and set up call forwarding based on the extension [1].

I haven't played with Asterisk before, so I'm not 100% certain.

[0] https://en.wikipedia.org/wiki/Asterisk_(PBX)

[1] https://www.voip-info.org/asterisk-call-forwarding/

[JdeBP]

Learn the lessons of SMTP-based electronic mail. Non-solutions like this just lead to an arms race. And indeed the other side already has a huge in lead this particular arms race. Voice recognition, speech-to-text, and DTMF generation are widely available telephony technologies.

[abawany]

Recent Panasonic cordless phones, which can handle cell calls if configured, have this feature. It lets the user define the 4-digit code that a non-whitelisted caller must enter before their call is allowed through.

[UI_at_80x24]

I don't pay for apps on my phone. I would $20 for that.