And to make sure the source is set to a value that the caller is allowed to possess. The problem isn't spoofing of numbers--because the utility is quite high for legitimate uses, like PBXes and after-hours doctor return calls for two examples--but the ability to spoof any number, not just numbers a caller is permitted to use.
PBXs? Surely you can get a block of numbers you’re allowed to have and use those.
After hours doctor return calls? Route the call through the physical office, or just call from a different number.
A system that’s overrun with spam is as useless as having no system at all. We got close to that with email in the late 90s and we’re getting close with phones today. Requiring some minor, inconsequential changes to how a few people use the system should be easily acceptable.
As useful as those examples may be, I am very much okay with cutting them off if it means we can greatly cut down on spam calls. People will adapt.
FWIW, I recently took the measure of setting my default ringtone to a "silent" sound file, and setting vibration to "none". Then I reenabled those settings manually for known-IRL contacts. A hassle to do, but absolutely necessary given the uptick in phone spam.
How about not sending them to voicemail?
I have literally _never_ used voicemail. I _will_ never use voicemail specifically because it has _always_ been riddled with spam. I even demanded T-mobile to disable my voicemail account. Not even six months later I started getting that annoying little icon on my phone again.
I really hope it’s a contact based whitelist.
I haven’t seen anyone write about this yet.