Transparent reallocation of control functions in IMS deployments

In this article we present a novel solution to transfer users between IMS network elements. This solution enables a home operator to perform an appropriate redistribution of load among the call session control functions of the IMS, which can be deployed as virtualized network functions or over dedicated machines. This way, the operator is enabled to adequately accommodate the instantaneous load generated by users to the available control resources, which may dynamically be activated or deactivated as necessary, as well as to enhance the resilient operation of the IMS deployment. Additionally, our solution does not require any change to the IMS specifications, and at the same time, the procedures are transparent to the end-user applications running at the IMS terminals. Finally, we describe some results obtained with a proof-ofconcept implementation of the procedures presented in the article in order to show the viability and correctness of our proposal.