The voice solution provides a way for the router to integrate into a Telecommunications and Internet Converged Services and Protocols for Advanced Networks (TISPAN)/IP multimedia subsystems (IMS) environment to provide voice over IP (VoIP) functionality. IMS is a flexible network architecture that allows providers to introduce multimedia services across both next-generation packet-switched and traditional circuit-switched networks. It uses open interfaces and functional components that can be assembled flexibly to support real-time interactive services and applications.
IMS provides a standards-based architecture that allows mobile carriers to migrate to next-generation networks that support applications that combine voice, video, and data functionality. The European Telecommunications Standards Institute (ETSI) created TISPAN to extend IMS support to fixed-line carriers. This extension is commonly called fixed mobile convergence (FMC). IMS/FMC allows subscribers to access any network (wireless or fixed) from any device (computer, PDA, or cell phone) and to move seamlessly from one network to another.
The router acting as a packet gateway provides much of the border gateway function (BGF), as shown in the ETSI-TISPAN architecture in Figure 10:
Figure 10: Routers Running JUNOS Software in the ETSI-TISPAN Architecture
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