making a phone call With just the email address

The other person has an apple device and has that email address as their Apple ID. You can connect to that person with an email address by using FaceTime Audio. Those calls are NOT going over the cellular connection. Those are audio calls completed by FaceTime.

Axel F.

Not sure what your callers are using without knowing what you are seeing at your side when you receive a call. My response above was that one can make a FaceTime audio call by using the other person's email IF the other person's email address is their Apple ID.

Axel F.