Bug fixes and other improvements We've created an updated version of Beeper Mini that fixes an issue that caused messages not to be sent or received. You can get the update directly from beeper.com/update on your phone. We are still doing some final testing before submitting the update to the Google Play Store for distribution to all users.
Basically if it’s using the email address then it’s using the iMessage transport, if it’s the phone number then it’s going over SMS.