I am running into a weird issue with the Cisco 9971 phone. We have it setup in a test (evaluation) environment to test against call manager 8.x and other systems as well. We managed to get the phone to register correctly everywhere, however we are running into a weird issue where during a call that is placed we hear a constant beeping tone being injected (every 5 seconds or so), almost as if "Call waiting" was turned on. However no call waiting is enabled.
Reading through some docs it seems that it may have something to do with line security, however this has also been disabled on Call manager.
Not sure if anyone else has had this issue or what one could do about it.