If the reason for requiring a phone number to use your service is spam prevention, why not add a secondary option that charges PoW or sats?
Discussion
This is the way:
Because most people don’t know what that means
But then they can't sell your data 😅
How about…
A system where you have to pay sats to use a 2FA, reset your password, or submit a password.
The catch is the sats go to your account wallet. So no harm if it’s you, as you’re paying yourself.
But bad actors won’t because of the cost of attempted log-in or attack.
Signal 👀... It would also probably cost a lot less for the infrastruture.