Buried deep in the recesses of the EULA, by just using your phone, you've agreed to allow your device to be tracked, simply by activating service. Triangulated from cell towers, your device [even if "off" (no more removable batteries?)] is communicating with the cell towers. Your device has a unique ID, and even though they "claim" no personally identifiable information is collected (don't be naive), if you track the ID long enough, you can tell where it goes from 5pm to 8am every day during the week (most likely their home), then from 8am to 5pm (most likely work), then cross reference that with property records, then those by employment records, and finally put it all in a database, then BOOM…YOU, as an identified person, are being tracked, 24/7.