When you make FaceTime calls on iPhone and iPad, recipients see your Caller ID ̵
When you call someone using FaceTime, your Caller ID is the email or phone number that appears on their screen. If you have many email addresses associated with your Apple ID, you have an even greater chance of calling people, one of whom is not recognized. This can cause calls to go unanswered or an unexpected email address to be shared with someone you do not want.
Changing the caller ID used when initiating a new FaceTime call is a relatively straightforward process.
To launch, open the Settings app and tap FaceTime.
Note that e-mail addresses are only displayed if you are logged in with your Apple ID. If you do not, make sure you're signed in and tap the "Use your Apple ID for FaceTime" button. 
Then tap the number or email address you want to use as the Caller ID in the Caller ID section.
And that's all that goes with it. When you start a new FaceTime video or voice call, the phone number or email address you just selected is used as your caller ID. This means that the receiver will also see it.