A telephone for use in ISDN telephone systems that implement advanced features such as call forwarding and a method for operating an ISDN telephone system to provide such advanced features are provided for. In an ISDN telephone system implementing the invention, the telephone communicates commands to the switching system by sending codes to the switching system. These codes normally denote keys on the telephone that have been depressed by a user of the telephone. A user of the advanced telephone features having a conventional telephone signals the switching system to activate the advanced telephone feature by depressing a specific key on the conventional telephone. In a system according to the present invention, a code having a value greater than any key code in any telephone in the telephone system is defined and an advanced telephone feature is assigned to that code thereby causing the switching system to implement that advanced feature when the switching system receives that code from a telephone over the network. A telephone according to the present invention includes a menu system that allows the user to select the advanced features implemented by the telephone system. The controller also includes a communication program that causes the switching system to download a list of advanced features implemented by the switching system, and the controller creates a menu item corresponding to each advanced feature identified in the list. In one embodiment of the present invention, the controller implements programs that simplify the use of the advanced features.