IP Multimedia Subsystem (IMS) is a standardized, open architecture based on SIP and the Diameter authentication, authorization and accounting (AAA) protocol. IMS defines how applications and services are delivered to customers, regardless of which network they run on. It separates session control from the actual applications for maximum flexibility, and can be used for centralized user profiles. It helps carriers to control sessions and provides the ability to charge for applications.
In addition to voice switching, control and applications carriers are also deploying data and video control layers, and IMS multimedia. They are also building more nimble and agnostic service layers with architectures such as NG service delivery platforms (SDPs). This area includes, for example, deployments of IP television (IPTV) and video overlays, as well as service enablers such as presence, instant messaging (IM)/chat, third-party exposure and application stores. The area is often associated with Telco 2.0.