Edit: What the fuck is wrong with me? I was thinking of Telegram.
~~Three words borne of cynicism. Everyone here is focusing on exactly three words as opposed to the point of my message. Signal logs phone numbers required on sign-up and associates them with user accounts. A "legal" warrant can easily acquire this information and potentially nullify any anonymization Signal provides. Signal doesn't have to require or retain this potentially identifiable information, but they do anyway.~~
My comment may have been a mistaken identity with Telegram, but you only have to download Signal to see that it still requires a phone number.