I hear interference all the time from cell phones/portable electronics. Out of every 20 planes I talk to I hear the tell-tale static at least 50% of the time. Most of the offenders are non-commercial flights, but even they have the static every so often. That being said, most of the time I don't care about repeating myself, but when I'm busy... the click-click-static-click pisses me off! Don't get a controller mad!