This can be solved with a backup that store the address book (but not in the cloud, please!). Signal for Android already have a safe and encrypted backup feature, I use it to keep my message history safe.
Not being forced to add a contact to the phone address book is an extra advantage, as address books are one of the first victims of spyware apps...
Also, with usernames and a desktop app, there is no reason to require a smartphone at all! Seriously, my Android phone is the least secure platform that I use at the moment (lots of proprietary stuff, spyware prone, ...)
Not being forced to add a contact to the phone address book is an extra advantage, as address books are one of the first victims of spyware apps...
Also, with usernames and a desktop app, there is no reason to require a smartphone at all! Seriously, my Android phone is the least secure platform that I use at the moment (lots of proprietary stuff, spyware prone, ...)