Notice: the app must be foreground. your itune music is your ringtone . select song from your itune ,then when the telephone call,the app can play selected song . if you only select playlist , the app play songs shuffle. Notice: 1.only for iphone ,only for os 4.0 2.the app must be foreground. 3.when the call entered, when you answer,then the caller first interrupt the call, the app enter the background,then you must relaunch the app to foreground. 4.when play music,the phone ringtone can play, so you can use the quiet.m4r as your default ringtone . quiet.m4r downloaded from http://www.1257.net/static/quiet.m4r.