Hi, I have just built a small messaging app where users sign up with their mobile number, and a verification code is then sent to their mobile. As soon as a user enters their name on the Sign Up screen, the account is created and the status is set to created. Once the enter their phone number, the account status is updated to pending. As soon as the enter the verification code, the account status is set to live. How should i handle the following case: A user signs up and is live on the app. They use it for 1 week, sending and receiving messages. The user looses their phone, and downloads the app on their new replacement phone, however the mobile number is the same as their previous account. What is the best option: A - allow the user to sign up on multiple devices with the same number (does this mean push notifications will be sent out to all of the devices AND all data will be downloaded to two devices) B - make the mobile number unique and destroy all the previous data when a user enters a new mobile number AND verification code (if they have entered the verification code, then they obviously own the phone, so we should delete all previous data for this person) C - any other suggestions Thanks in advance for your help.