In X-IPS, we should not develop OSA Gateway (Service Capability Server) in this project. The reasons are the lack of human resource and OSA SCS should be developed by headquarters in order to provide full Service Capability Features which point to Xener's network functional entities.
Otherwise, if we decide to develop our own one, from my point of view, we just can develop Presence Server's Service Capability Feature.
When buying fulled-IMS packages to certain Network Operator, we could associate Presence Server as free. Another server such as RLS, XDMS, Content Server, PNA, OSA SCS will be optional to customers if they want to buy.