I want to know what the best way to achieve this scenario. I have a DN, lets say x2000. One phone always has this number. I would like to have other phones / users to be able to back this line up (answer calls) if it is busy. I also need to be able to have those other phones / users to be able to remove x2000 if they do not need to back it up that day. Is there a way a user can add and remove a DN on a day to day basis similar to Extension Mobility?