Switching smartphones, although as exciting as it could be, has to be done correctly to ensure the best experience possible when using Beeper on an iPhone and iMessage connected.
How to switch from iPhone to Android while using iMessage on Beeper?
The steps are simple but essential to ensure you don't miss any message on Beeper Android while switching your phone number from iMessage (iPhone) to Android SMS.
First, and before switching devices (and removing the SIM/eSIM from your iPhone), on your iPhone, go to Settings → Messages → Send & Receive and deselect your phone number. This will remove your phone number from Apple's servers as an iMessage alias.
Next, go to Beeper Desktop. Go to the Gear icon → Chat Networks → iMessage. Verify that your phone number is no longer linked to iMessage on Beeper and set your "default alias" of choice.
Now you can sign out from Beeper iOS, swap the SIM/eSIM to your new Android device, sign in to Beeper Android, and set up your SMS Bridge.