Most of the time when my iPhone 7 makes the bluetooth connection to MMI, the audio goes off and the MMI indicates that it is connected on a call. The call timer is running but End Call doesn't work. The phone shows no evidence of being in a call. Actually making a call on the phone and then hanging up (again on the phone) clears up the problem until the next time the phone connects with the car. Resetting the connection and re-installing IOS has not helped.