Abstract: SIP-based VoIP systems use C/S architecture, which brings two intrinsic issues when the user number grows to a large scale, namely single point of failure and performance bottleneck problems. The systems based on P2P-SIP are scalable and fault-tolerant. However, existing systems cannot meet the administrable and maintainable requirements from the service providers. The authors propose an administrable and manageable VoIP system based on P2P-SIP, called AMAP. In an AMAP system, a number of servers, deployed by service providers, form a DHT-based service overlay network, which provides services for the user agents, such as registration, session initialization, etc. The AMAP system leverages extended SIP messages for the overlay maintenance and, thus, is compatible with traditional SIP-based VoIP systems. To further improve the fault tolerance and relieve the hot spot problem, the AMAP system replicates and caches the user information on the service overlay. A distributed meta-data aggregation and dissemination algorithm is proposed to support the management. This algorithm leverages the tree structures which are implicitly defined on the service overlay based on DHT nodes' finger table. The analysis results show that, compared with existing VoIP systems based on P2P-SIP, the AMAP system reduces the maintenance overhead by 80%. A prototype has been implemented and some functional tests have been performed.