Cont.What is Beeper?
Beeper is a universal chat app. With Beeper, you can send and receive messages to friends, family and colleagues on 15 different chat networks, all from a single app. Beeper is free to use, with optional paid subscription. You can use Beeper on all your devices at the same time — your messages sync seamlessly across all of your iPhones, Androids, iPads and computers.
Read it all before commenting , the obvious security/encryption issues are addressed, some will be insurmountable but for replacing many of my casual messaging apps it could potentially work. I'd keep Signal off of it though and use that app exclusively direct.
There's a few reviews of it in the tech press - all raise similar questions about its sustainability in an environment where the big players like Apple/FB/Google/MS will change their API's at the drop of a hat and may start blocking IP addresses...