Yeah there is a phone number. Usually it doesn't work for calls or SMS, or you can have that blocked for it. It's not worth using or thinking about. IMessage and Facetime work with email addresses, whatsapp and signal can be associated with any phone number, and don't need to use the one on your SIM card.
Doing FaceTime audio or a VOIP service is at most half-a-MB per minute, and th call quality usually way better than regular cellular. Cheap over LTE, and inconsequential over wifi.
Doing FaceTime audio or a VOIP service is at most half-a-MB per minute, and th call quality usually way better than regular cellular. Cheap over LTE, and inconsequential over wifi.