As helpful as it is, caller ID doesn't really tell you everything about who's ringing your phone or why. Is it an acquaintance? A best friend's birthday? Or a robocaller? Facebook might have a better solution. It's rolling out Hello, the previously leaked Android caller ID app. The software shows all the Facebook information that a caller is willing to share, whether it's public or between friends -- you may know who someone works for even if it's the first time you're speaking together. You can also find out how many times a number has been blocked, automatically block the worst offenders and search for people or places. Facebook is only offering Hello in Brazil, Nigeria and the US right now, but it won't be surprising if the app spreads elsewhere before long.