Anyone who uses their iPhone to pick up calls, whether they're phone calls or FaceTime calls, knows that when music is playing, iOS will automatically pause the music until the phone call ends. When it does, iOS will resume the song where it left off.
Those who don't like how the music resumes after a phone call really have no way to disable the feature on a stock iPhone; instead, you would have to go back to the app that is playing the music and pause it manually.
A new free jailbreak tweak called PauseAfterCall solves this problem.