Missed call alert sound

Does anyone know where the "missed call alert sound" is? I'm used to hearing a sound every minute or so when there is a missed call during those times when I can not physically pick up the phone. On the iPhone, I have to actually look at the screen to let me know that I have missed calls. In Settings, you can turn on/off a sound for voicemail but not missed calls. Where do I go to set a sound alert for missed calls? Thanks