Earlier quoted context omitted.
I haven't tried it, but Signal supports not sharing your phone number/just communicating with usernames: https://signal.org/blog/phone-number-privacy-usernames/ You still need to use your phone number to sign up, though.
> You still need to use your phone number to sign up, though. Which defeats the whole point. What if the FBI politely asks Signal about a phone number?
So the FBI cant ask what phone number is tied to an account, but if a specific phone number was tied to the specific account? (As in, Signal gets the number, runs it through their hash algorythm and compares that hash to the saved one)
But my memory is very very bad, so like i said, i might be wrong