Signing up on donotcall.gov doesn't help. There's always some checkbox in some terms of service somewhere that grant people the right to contact me that I don't know about.

But the biggest reason I don't want to give my phone number is I want to not feel the way being required to give my phone number makes me feel. I feel like a tracked inmate.

Right back at you: why do you need a phone number from a user? Why do you need anything from a user? What problem are you trying to solve that cannot be solved in any other way except by asking for people's phone number?