The Android app requires at last Android 4.3 to run. Previous versions are not compatible to Bluetooth Low Energy and so won't work.
iOS Version 6.1 or later required, because of the Bluetooth Low Energy capabilities.
- Nexus 4, Nexus 5, Nexus 7 (2012 and 2013 Version)
- most Android devices with Android 4.3 or newer
- iPhone 5, iPhone 5C, iPod Touch 5
- iPhones with iOS 6.1 or newer