The IP multimedia subsystem (IMS) has emerged as the standard architecture for delivering multimedia services---text, audio, video, ec.----across both wired and wireless networks. This is the very applications-oriented guide to IMS, giving telecommunications engineers and networks administrators the pragmatic, ";hands on"; details they need to successfully plan, design, and implement IMS networks. Topics discussed include subscriber identification and addressing, session control, interleaving multiple services, converging IMS with other network, and security issues. Special attention is given to developing end-user interfaces and IMS applications servers. IMS network monitoring, management, and performance analysis issues are also described in detail. This is the essential reference for anyone needing to quickly understand IMS and successfully create IMS networks.