Does anybody know what messaging app notification is a square chat bubble with blue outline and the capital letters BR inside? Or It could be RB inside the icon .
I'd like to recommend creating a account so me or other members can assist you, as guest have limitations in replying here and if we need further Information to communicate with you.
Welcome to Android Central! Just swipe down the notification panel -- the app name should be associated with the notification. If not, then long-press it and tap App Info.
If it's not your phone, then as Galactic Zoo suggested, ask the person who owns it.