Identify if a user is online in Google Hangout How can I know if a user is online or offline in Google Hangout? In the Hangout on Gmail web it shows a green line under the user's profile pic. But there no such thing in Android app.
Hangouts doesn’t use the green or grey dots that Google Talk used to identify if someone is online or offline. Instead, you can tell if a contact is online or not  if their profile picture is clear or faded. A faded profile picture means your contact is unavailable, and a clear picture means they’re online. One downside is that Hangouts doesn’t support the “invisible” status like Google Talk did