Support for multiple SIM cards and high-definition sound in telephone calls are two of the features Google has announced will be included in the pending update of its Android 5.1 system, the successor to Lollipop.
The new system also provides theft protection, with the ability to freeze up the phone if an unregistered user tries to return the phone to its factory settings. It can then only be unlocked if the owner registers himself on the phone with his Google account.
The Nexus 6 and 9 devices will be able to support this Device Protection feature, as should most other smartphones and tablets that carry the 5.1 update.
Of course, all of these services will only be available if the telephone being used actually supports them.