Development of the architecture for Voice Call Continuity has identified that supporting domain transfer of active midcall services by implementing these services in both the CS domain and IMS is not a viable solution in the 3GPP Rel-7 timeframe. Therefore it has been proposed that an architecture is necessary that allows implementation of such services in IMS while also allowing control of the services when the serving access network is the CS domain. In addition to the VCC scenario, the increased deployment of VoIP capable access technologies will encourage further service development on IMS also increasing the importance of being able to access these services via CS domain access independently of the support of VCC.
This TR contains the results of the feasibility study into the architectural requirements and alternatives for the delivery of consistent services to the user mainly via IMS centralized services regardless of the attached access type; e.g. CS domain access or IP-CAN. Considerations include overall requirements, architectural requirements, alternative architectures and evaluation of potential architectural solutions.