

While both charts seem to end at approximately the same time, and both contain 8 entries, they don’t really corollate well except for two that I have circled. I suspect that the earlier entries on both devices were instances where the iPhones checked for new data.
I suspect that the highlighted entries are two FaceTime calls between the two iPhones. I had wondered if the amount of data used would be the same. Clearly, they are not. In talking with Monique and Sandy, some calls were initiated with Sandy pressing the FaceTime Chat button while in other cases, Monique pressed the button.
I think the best call to compare is the top one. Unfortunately, we can’t determine which iPhone initiated the FaceTime portion of the call. It is also interesting to note that the Session Start and End Times vary as does the amount of data used.
Here are two more entries to analyze:
![]()
![]()
Although both calls began at the same time, there is a difference in ending time. One possible answer is the hospital’s WiFi network. It is slow, weak and problematic most of the time, but occasionally, things seem to “click” and it can support decent speeds and signal strength. I suspect it strengthened and took over the wireless duties at some point in the call. There are several other occasions in the data records that seem to indicate that a call transferred between the two wireless networks.
In any case, the amount of data being transmitted during a FaceTime call is in the 1 to 3 MB per minute range. Doing a little research, I found an article on 9to5mac.com that seems to support this. I suspect the data usage rate has much to do with the amount of movement in the camera’s view, just as happens in video capture with a camera.
My conclusions are that interpreting MiFi usage charts is not a simple task. Also, I will not hesitate to make FaceTime chat calls to family and friends. They are economical in their data usage and a wonderful way to share events.
--Pat