Abstract: An on-demand teleconferencing system and method for an Expanded Conference Call (ECC) initiated by dialing an ECC Access Code when originating a new call to a Conference System, or causes an active two party or three-way call to be connected to a Conference System to allow a greater number of parties to participate in the conference call. A subscribing party initiates ECC by dialing an abbreviated ECC Access Code consisting of a dialing sequence of less than seven digits. The original two or three-way call participants in an active call are automatically connected to the conference system after the subscribing party initiates ECC without having to disconnect and originate new calls.