March 9, 2017; 7 years ago (2017-03-09) (as Google Chat)Some messaging services that are not designed for privacy require a unique phone number for sign-up, as a form of identity verification and to prevent users from creating multiple accounts.
Some messaging services that do not solely focus on a mobile-first experience, or enforce SMS authentication, may allow email addresses to be used for sign-up instead.
Examples of such messaging services include: WhatsApp, Viber, Line, WeChat, Signal, etc.
Messaging services with a multi-device model are able to eliminate feature disparity and provide identical functionality on both mobile and desktop clients.
Desktop clients can function independently, without relying on the mobile phone to login and sync messages.