sort of related, I wish phones generally allowed extensions.

In other words, phone number plus a 6-digit extension, otherwise voicemail.

Sort of like your code, but allowing a person to talk to you in the first place.

Not exactly the same, but wouldn't it be possible using a VOIP service like Google Fi to have/generate a large number of phone numbers? Give each contact their unique number, so if you ever get spam called you can detect where your number leaked from.

(If it isn't directly possible, I'm fairly sure using some sort of iot telephony servive would help getting hundreds of legitimate numbers. Now only to build a cell interceptor to funnel them all to one phone!)

I don't think Google Fi is a VoIP service? At least, not any more one than any other cellular provider in these days where "WiFi Calling" is widespread.

Last I knew, they used T-Mobile for their cellular connection.

this is technically possible at the phone level, but all the business infrastructure enforces ten digit validation.

it's a wish, probably a fantasy.

but it could be like letting smart people organize their life using email addresses in a similar way: [email protected]

Pshaw, next thing you'll be saying companies have to be liable when criminals fool their employees rather than pushing all the consequences onto innocent customers under the phrase "identity theft." :p