Best practices: registration based on phone number in mobile development (how)?

Question

Mobile development

I am writing a mobile application on react-native (only android) and the task is to implement user registration based on a phone number, and also subsequently have a relatively speaking permanent session. Similar mechanics implemented for example in telegram. But I don’t understand on the basis of what (session, jwt, api token or something else) to implement automatic authorization on subsequent application launches, in fact, I don’t really understand the flow itself.

Answer 1

If it is as simplified as possible:
1) We check the uniqueness of the phone
2) We confirm the ownership of the phone
3) We write out the Auth-Token stored in the application and in any storage.
4) We monitor the relevance of the Auth-Token: when logged out, we delete it from the storage, at the end of the lifetime - too.
5) At the start of the application and subsequent server-client-server communications, we helmet and validate the AuthToken.