An account with this phone number doesn't exist on telegram: the user has to enter basic information and sign up
auth.authorizationSignUpRequired#44747e9a flags:# terms_of_service:flags.0?help.TermsOfService = auth.Authorization;
|flags||#||Flags, see TL conditional fields|
|terms_of_service||flags.0?help.TermsOfService||Telegram's terms of service: the user must read and accept the terms of service before signing up to telegram|
How to register a user's phone to start using the API.