yments of new VMs/VNFs. Even initial field deployments will look more like capacity expansion efforts than new technology deployments. 14.4 CURRENT AND VIRTUALIZED SERVICE PLATFORM USE CASES This section provides a view of some of the key service platforms and services, their current imple- mentations, and virtualized implementations. 14.4.1 IMS SERVICE PLATFORM IMS is an architectural framework that provides a standardized way to deliver multimedia ser- vices over an IP network. IMS further enables fixed-mobile convergence by providing the ability to access services over wireless and wireline access. The session control layer isolates the access layer from the applications layer to enable access to agnostic IMS-based services. 14.4.1.1 Current Implementation Current IMS service platform implementations are multivendor platforms that provide voice call processing and messaging support to multiple VoIP services such as VoLTE. IMS service platforms maintain the layered architecture with the access, core, and AS layers. Access nodes contain border elements (such as session border controllers [SBCs]) that provide access from a geographic region and interface with the core network (CN) functions. The CN functions interface with various ASs that provide services. Figure 14.12 shows the various components of an IMS-based service platform and the interfaces to other networks. In addition, the platform also contains surround support components for opera- tions and maintenance functions including vendor-provided EMSs, software upgrade servers, audit- ing tools, and physical probe elements with interfaces to OSS, BSS, and billing systems. IMS Service Platform VoLTE Transit Function SCC-AS /BGCF CALEA LI Gateway Standalone Media I/S/E- -I-CSCF Gateway Interconnect Session Border Access Session Controller Enforcement Border PSTN/ Controller Other carrier Business networks Service Platforns Consumer Service Platforms FIGURE 14.12 IMS service platform components and interfaces. Service Platforms IMS service platform implementat