Its a friendly reminder to turn your phone to SILENT (NOT VIBRATE) when you enter the studio., WHY? , Because we often have private training or classes taking place in one side of the studio and Cool phone tip I just learned You can keep your phone on silent and still hear calls or texts from specific people like family, close friends, or co commanders . Here's My iPhone Doesn't Vibrate! Here's The Real Fix. Tuesday Tip: Why your cell phone won't ringand how to fix it CREDO Mobile Blog