We have just run into this issue, the user has a standard Yealink phone in the office (on the same network as the 3CX Phone System) and we are trying to configure a Yealink Router Phone for the user to have at home but it looks like we will have to delete the standard Yealink phone first so that we can then add the Yealink Router Phone and then go through the process of provisioning the standard Yealink phone in the office again! This is really disruptive for the user and time consuming for us when all we want to do is add a single Router Phone to an existing users extension. Please can you clarify 3CX Support? Is this something you are planning to resolve in the next update for Version 18?