Apple's proprietary iMessage system lets iPhone users send text messages to other iPhone users over a data network, avoiding SMS charges and making texting free, at least within Apple's ecosystem. It's an impressive run-around of the entrenched carrier system - the same basic idea, applied to an agnostic model, has made texting alternatives like WhatsApp fantastically popular. But users found that trying to leave Apple's walled garden was much harder after setting up iMessage with their personal phone numbers.
"Burner" cellphones, pre-paid phones that are used and discarded, have become a handy way to protect your identity if you find yourself dealing with people you might not otherwise want to meet. Just lately it has become possible to get "disposable" phones without the phone, thanks to apps like Hushed, which provides a limited-use virtual number that can be easily substituted for your real one. Burner is a new competitor in the same vein, happily landing on Android after considerable success on iOS.