Sending as Unknown number in Hangouts In Hangouts 3.1.89134953 I get a "Sending as Unknown number" message at the top of my texts.  I googled for this message and found nothing. 

What does this message mean?
You most likely are not registered for hangouts. Try navigating to hamburger menu -> Settings -> [your email] -> Scroll to Account section, and check to see if your phone number is confirmed.