If your Apple ID is a phone number
How to Check Apple ID on iPhone or iPad
This can be a frustrating problem, and it usually takes two forms. Not good. However, there are a number of solutions to this problem.
How to Find Your Apple ID
Subscriber Account active since. You aren't required to have an Apple ID to use an iPhone , but without it you won't get the most out of your phone. You need an Apple ID to unlock some of the most convenient features of your phone. When you first set up your iPhone or any other Apple device , you are prompted to enter your Apple ID. If you don't have one, you can create an Apple ID at any time. You should have only one Apple ID though some people have more than one. Your Apple ID is an email address. It can be an Apple email address: icloud.
You might want to protect your privacy, or maybe you just want to use a new email address instead. Your Apple ID is the account name that you use to log in to all your Apple devices. Your Apple ID is also used to set up all your subscriptions, to use the Find My app so you can find your lost Apple device, to download old purchases, and more.