Not a phone, But I left a Garman GPS on the tail of a 4 seat airplane I was flying during the pre flight, still in the tie down. Well, hour in to the flight I realize it's missing, and immediately remembered what I had done. Get back to the airport and just in case if it's my 1-million shot day, I contacted airport maintenance to see if they would drive down the runway I used and take a quick look. Well sure enough a few minutes later here comes the maintenance guy in his truck with a big grin on his face. Antenna a little tweaked, but still dutifully reporting lat/long. Given the spot on the runway where he found it, it hit the asphalt at a minimum of 60 MPH.