Change of phone number
In iMessage and FaceTime on my 6s iPhone showing old phone number and after trying to change it showing “activation unsuccessful”. How to change my new number
iPhone 6s, iOS 12
Go to settings>> [yourname]>> name, phone numbers, mail>> tap on edit and add your current phone number
https://support.apple.com/en-jo/HT201349 <--- see more here
Regards.