So here is the situation, I just got to know a certain person and I was recently notified through my Line that he added me as his friend. I have his phone number but he doesn't have mine. All he has about my contact is my e-mail. However, when making a Line account I was not asked to input my e-mail. How can he find me in Line then? The only explanation I can come up with is that this app is able to associate any e-mail accounts registered in the smartphone in which this app is installed with the number used by that phone. But if that's true, then if I purposely enter someone else's phone number to make Line account using my own smartphone in which my e-mail is registered that will cause this app to falsely identify the phone number as mine.