Seamless roaming in heterogeneous circuit-switched and IP networks is key for successful migration towards all-IP. The Unified Mobility Manager (UMM) keeps track of users’ locations whatever network they are roaming, and that routes calls from any originating to any terminating network. In a UMM enabled network, calls are addressed to users and dynamically routed to the active devices. This notion of user mobility breaks up the traditional coupling of addresses and devices, and replaces it with rules for the dynamic mapping from logical to device addresses. We present the UMM multiprotocol subscriber base that is built upon the concept of Incoming Call Handling (ICH) profiles that are the addressable entities in the UMM. An ICH profile contains all address level service data as well as the routing rules to the actual terminating devices. We also present our implementation of the UMM subscriber base in detail, and compare the UMM approach with two other approaches – a federated app...