My app communicates between 2 users.

User ‘A’ sends a statement which is posted on my website aimed at User ‘B’. He does this using User B’s phone number.

User ‘B’ now accesses this by submitting his own phone number.

As I understand it, accessing the linenumber of the phone is not allowed for security reasons.

However, I’m worried that anyone can access the message if they know User B’s phone number.

The App doesn’t need to know the user’s phone number, just make sure that the phone is who it says it is.

Is there a way to validate this using Kotlin in Android Studio?