For what it’s work, as far as I know, Signal has never claimed to be an anonymous communication service. They are a secure communication service. This means th

For what it’s work, as far as I know, Signal has never claimed to be an anonymous communication service. They are a secure communication service. This means they minimize the information that is in the clear and do this quite well. Now to your specific concern about the phone number. Signal only has your phone number and sign up time. This means that for someone to request your information, they’ll pretty much need that already. If you look at the subpoena you’ll see that the FBI is asking for data associated with the persons name or phone number. Name is something Signal doesn’t have. You’re right that it’s trivial to get with the phone number (and the FBI has obviously done this), but they must necessarily have this information to even request data from Signal. In other words, Signal doesn’t provide a means of leaking your name. What using a phone number identifier does do is allow someone to go from name to phone number to Signal request, though that Signal request with turn up very little data.