The timer feature on the iphone still plays the alarm even when the external mute switch is engaged. Found this out after pissing off a theater full of people when I couldn't get the Marimba alarm to stop. First of all it was in my coat pocket, which I couldn't reach easily. Then I tried flipping the mute switch off and back on and pressing all the buttons. I finally had to completely pull it out then slide the screen slider to get it to stop. I don't know if this is a bug or something intentional, but I use my silent switch on a fairly regular basis - especially in meetings. Gotta watch it now!