A technique for providing real-time multimedia conferencing services with guaranteed performance, in a hybrid networking environment, by interconnecting ADSL modem-based premises networks via ADSL access networks and an ATM wide area network is disclosed. A functional design constitutes both component and protocol architecture of an ATM ADSL modem for both premises networks and headend stations of the ATM network. The ATM wide area network may be divided into a plurality of access network domains and one backbone network domain to provide efficient and intelligent multimedia conferencing services. Each ATM access network domain has one ADSL modem server as well as access multimedia bridge server, while there is only one central network server and one central multimedia bridge server within the backbone network domain. Each ADSL modem server located in an ATM access network domain maintains necessary information of how the bandwidth of the ADSL access network is being used by existing calls, and how the ADSL line bandwidth will be allocated when new multimedia conference calls are initiated, in accordance with the desired priority and performance levels. If all conference participants are connected to the same ATM access network domain, the access multimedia bridge server of that domain will provide bridging, otherwise the central multimedia bridge will provide bridging. An integrated call control algorithm and cable modem control and signaling protocol scheme has been developed to set up multimedia conference calls that guarantee bandwidth over the ADSL access network as well within the wide area ATM network.