The smartphone system sends data to the Dexcom server, where that data is made available for reports. To receive this data, the smartphone needs to be connected to the internet and have the Dexcom Mobile CGM app running.

The Dexcom receiver requires connection to a computer to upload the data periodically. If you use a smartphone part of the time and a receiver part of the time, then Dexcom CLARITY needs data from both to provide accurate statistics.