To activate the EMU feature, a user enters the EMU activation feature-access-code (FAC), the extension number of their primary telephone, and a security code on the dial pad of a visited telephone. The visited server sends the extension number, the security code, and the set type of the visited telephone to the home server. When the home server receives the information it:

• Checks the class of service (COS) for the primary telephone to see if it has PSA permission.

• Compares the security code with the security code on the station form for the primary telephone.

• Compares the station type of the visited telephone to the station type of the primary telephone. If both the visited telephone and the primary telephone are of the same type, the home server sends the applicable button appearances to the visited server. If a previous registration exists on the primary telephone, the new registration is accepted and the old registration is deactivated.

If the registration is successful, the visited telephone assumes the primary telephone’s extension number and some specific administered button types. The display on the primary telephone shows Visited Registration Active: <Extension>. The extension number that displays is the extension number of the visited telephone.