I have a customer who has one phone in their office that randomly sends out a blinking red light to the other phones in the office for her extension. In other words ext. 14 appears blinking red on the other extensions in the office...the only way to make it stop is to put on her DND so it is solid red, or to walk over to ext. 14 and lift the handset. Then it's ok for a while, but will eventually start blinking again, whether she is at her desk or not. Any ideas?