My freind showed me this thing on his phone where he dialed some # (which he wouldn't tell me) and I heard some recording then he pressed some other buttons, put it on speaker phone and hed end up with some celebrity's voicemail like T.I, Miley Cyrus, Tyga or Rhiannaas if he had actually called them. What is this service or # and how do you do it? How does it work? How can I do it?