This paper presents a mobility management solution to support both applications who are mobility-aware and those who are not. Mobility management in heterogeneous network environments needs to address the double meaning of the IP address as an endpoint identifier and a location identifier. Application-layer mobility use a non-IP endpoint identifier (e.g. user @ realm) while network-layer mobility uses a fixed home IPaddress as endpoint identifier. The resolving of the endpoint identifier to a temporary unicast IP address as location identifier needs support from a mobility management system. This paper proposes a mobility support system that integrates the benefits of application-layer SIP mobility with network-layer MIP mobility. A cross-layer information system provides context for mobility adaptation. Context awareness enhances handover decisions, transport performance and media adoption. The network-layer mobility supports the application to locate the destination ondemand for the initial setup of the sessions. The paper includes an initial evaluation of the network-layer mobility part of the solution.