IP Multimedia Subsystem (IMS) is an architectural framework for IP Multimedia communications and IP telephony based on Convergent applications. It specifies three layers in a telecom network:
Transport or Access layer: This is the bottom-most segment responsible for interacting with end systems such as phones.
IMS layer: This is the middleware responsible for authenticating and routing the traffic and facilitating call control through the Service layer.
Service or Application layer: This is the top-most layer where all of the call control applications and Value Added Services (VAS) are hosted.
IMS standards are defined by Third Generation Partnership Project (3GPP) which adopt and promote Internet Engineering Task Force (IETF) Request for Comments (RFCs). Refer to http://www.3gpp.org/technologies/keywords-acronyms/109-ims to learn more about 3GPP IMS specification releases.
This chapter will walk us through the interaction of WebRTC client with important...