How much data does FaceTime audio calling use?
FaceTime audio calls can be made over Wi-Fi or cellular data (3G / LTE) connections. While a FaceTime audio call will not use any wireless plan calling minutes, it does consume data.
The amount of data used by a FaceTime audio call varies, but it is significantly less that the amount of data used for a video call.
Five minutes of FaceTime audio calling uses up to 3 MB of data.