Only use this tag if your question is specific to Android 5.1 Lollipop, an incremental update over 5.0 announced on March 9, 2015.
Announced on March 9, 2015, Android 5.1 is an incremental update to Android 5.0 which maintains the "Lollipop" moniker. It introduced several new features, including:
- Support for multiple SIM cards
- Device Protection
- High definition (HD) voice on compatible phones.