IV. Possession of a compatible (Android, iPhone 5s or later; OS 8.1 or higher) smartphone with an active phone number and data plan. The smartphone must be in continued possession of the subject. It may not be a shared device and must exclusively remain in the possession of the subject during the study period. The smartphone must have an active cellular phone number and cellular data subscription. Wi-Fi internet capability is not a substitute for an active cellular data plan.