Apple's FaceTime might make it a little too convenient to drop in on a friend. Reports have emerged of a bug that lets you listen to the other side's audio before a call has even started. All you have to do is start a FaceTime call, add a person, and choose your own phone number when prompted. If you try that, you effectively start a group call while the other side's device is still ringing. It's not necessarily eavesdropping, especially when the other side can hear you, but it could easily lead to catching someone off-guard.