The purpose of this Recommendation is to define the multimedia conference services based on IP networks. The service provides real-time communication between several users in different locations over an IP network. The service description, functional model, application scenarios and requirements of the IP multimedia conference services are provided. The IP multimedia conference service is one class of the generic services identified in ITU-T Rec. F.702, and its description follows the methodology described in ITU-T Rec. F.701. The requirements for the IP multimedia conference services are derived from the scenarios for different applications the said services can support. Therefore, the services requirements accommodate the demands of different kinds of users and assist in enabling intercommunications between the services systems provided by different telecom operators, or between the equipment manufactured by different manufacturers.