Avaya phone system. The 8410D handset for a particular extension will not show the incoming caller id. When the extension is moved to another handset/line the same thing happens - no caller id. A different extension on the original handset/line works fine and displays the caller ID. To my observation, the problem is in the programming of that extension somehow, and it is the only extension in the building that is having the issue. I have looked a dozen times at each and every possible setting but cannot figure out why this one extension refuses to show the incoming caller ID. It seems to work fine otherwise. Has anybody ever seen this problem or have any ideas?