Yes, the Billy kit works with the Billy app on your smartphone.
This is important for the family members so they can see key insights, but it's also valuable for you too. While Billy will still work without a smartphone, we use technology in your phone to know whether you are home or not. For example, we don't want to notify your family that you've missed a meal if you've gone out for lunch with friends.
Billy will work on any iPhone running iOS 9.0 or above, or any Android phone with Android 5.1 or above.