Authorization like Viber? How does it work?

Question

Mobile development

Hello
I want to make an application, something like a navigator on the phone. But I don’t quite understand how authorization works in applications where you only need to receive a message with a code once, activate it and that’s it. And how then authorization passes?
How does the protection work so that you cannot send a message from another user (even without access to his phone)? Those. you send not from yourself, but from some other number to which you don’t have access, but in general .. How does it work?

Answer 1

token based auth