Your account on a second phone
Point the new phone at a square on the old one and it is yours too, without spending a recovery code. Each device has its own key, so a message is encrypted for every phone you hold and for nobody else's, and a device you have lost can be dropped from the account on its own.
How it works
On the phone you already use, choose Open Siren on another device and get a code.
Point the new phone's camera at the square, or type the code under I already have an account. It works once and lasts five minutes.
Each device has its own key, so every new message is encrypted for all the phones you hold.
A new phone cannot open what arrived before it. Your old phone can send it the keys, once six words match on both screens.
Where to find it
You → Devices and alerts → Open Siren on another device.
What it will not do
Siren cannot move your history to a new phone by itself. Only a phone of yours can, and nobody opens your messages along the way.
Why it works this way
Recovery codes are for the day you lose everything, not for adding a laptop, so a second device should not spend one. Keys that belong to each device mean a phone you have lost can be dropped from your account without touching the others.
Free forever, for every woman here.