Digital telephones offer the possibility of setting up a network-wide "witness" connection during internal or external calls. The prerequisite for activating a witness connection is that the user activating the facility is called directly. This means it is not possible to activate the witness facility for a consultation call. The witness is connected without a notification tone. The ITR group's witness (analog telephone) can be dialed automatically by pressing the witness key. ITR groups should be used to ensure that users have set a permitted ITR as the witness facility. One witness station can be added per ITR group.