This service allows the user to barge in on a call to or from another user in the same group, by entering the feature access code followed by the extension of the user whose call is to be barged-in on. Barge-in is successful only when the second user has only that one call. When a user barges in on an answered call, the call becomes a three-way call and the user who barged in becomes the controller of the three-way call. The company administrator configures a tone that warns users on a call that another user is barging in on their call. By default, users are prevented from having their calls barged-in on.