An analysis of capital expenses and performance trade-offs among IMS CSCF deployment options

Service providers around the world are deploying or planning to deploy the IP Multimedia Subsystem (IMS) in their core networks. IMS allows the delivery of new multimedia applications that can enhance the user's experience and bring in new revenue for the operators. These operators are now faced with deciding how to best deploy the various IMS functional elements in their networks. In this paper, the authors provide a survey of the various options available to the operators and present an analysis of some of those deployment options. In particular, the paper addresses questions around the advantages and disadvantages of centralizing or distributing control functions such as the call session control function (CSCF) in terms of capital expenditure (CAPEX) costs and latency trade-offs. Without the proper deployment strategy, there can be major differences in the overall cost of the network and therefore it is important to perform such an analysis. Initial recommendations and general observations are given that can assist network planners and operators to more efficiently develop an IMS deployment strategy. Further analysis and study that includes operational expenditure (OPEX) costs should also be factored into the final decision.