The transmission of multimedia streams with a particular and guaranteed quality of service (QoS) is a major challenge in multimedia communication over IP networks. In this paper, we analyze the distributed architecture of a Video on Demand (VoD) system to design global request handling and admission control strategies. We describe a highly available distributed VoD service using existing telephone network, which is inherently scalable and fault tolerant. The VoD service is provided by Media Server Farms (MSF), which may reside in different local telephone exchange of a telephone network. We present the design and simulation results for a new distributed admission control and QoS adaptation controller architecture, called Semi-Distributed Admission Control (SD-AC) architecture for a set of MSFs.