Once you’ve set up Facebook Messenger for your business, some of the symbols and icons on Messenger’s interface may seem foreign. What do the Facebook Messenger symbols mean? An open blue circle with a check mark shows that your message has been sent. i'm unsure what the symbol beside mobile means?. Facebook Messenger is a common tool that many of us use to contact From here, tap the 'Add contacts' icon in the top right-hand corner - a.