For the few years following Apple’s first-generation iPhone debut in 2007, it seemed almost impossible to avoid a chorus of “Tri-tone” iPhone text alerts at every turn. The tone still seems to pop up all the time in public, and while it’s easy to take something as simple as a ringtone for granted, it’s also quite interesting to get the back story on one of the iPhone’s two most famous tones. Former Apple engineer Kelly Jacklin recently published a piece on his site that gives the public its first ever look at exactly how the famous Tri-tone alert came to be. The tone’s development dates all the way back to before Apple’s 2000 acquisition of SoundJam MP (which would later become iTunes) when Jacklin was approached by one of SoundJam MP’s co-founders to create an audio alert that would let users know when a CD had finished burning. The rest, as they say, is history. Jacklin’s account, which is linked below, is a great read — and as an added bonus, he includes a sampling of several other tones he created that didn’t make the cut.