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. If you encounter any issues, you may need to uninstall and reinstall the app.
Here is their POC in Python:https://github.com/JJTech0130/pypush
And their article explaining it: https://blog.beeper.com/p/how-beeper-mini-works