I have this strange problem on my iPhone 6 - 128gb - iOS 8.1.2 - never jail broken. This happens once in few days. Problem - when you have your phone on silent mode and when you receive a call, your phone keeps on ringing/vibrating. Phone doesn't stop ringing when you answer the call/switch of silent mode/lock the phone. The only way to solve this problem is to restart the device. I'm not sure if this is related to software/hardware? Please let me know if any of you had this issue and resolved. Any suggestions appreciated. Thanks.