Just out of the blue today, on a phone call with my BF, he took another call and when he did so, I heard hold music playing. We are both on AT&T, I have an iPhone 6s+ and he has an iPhone 6s which is jailbroken, but he hasn't done anything to change it where it would play hold music. We tried it three separate times and the same music played each tie. I don't know of any way to play hold music on an iPhone. Does anyone know it happened?