I have three T7316e on a R3 BCM 50. Each phone has 3 trunks and 2 intercoms. The trunks can be pressed and make a call. But when you press an intercom key you get a tone and 'no button free' The phone is idle at that moment. The rest of the phones have no issue (about 10). I am not certain what could be the trouble. Is a reboot necessary?