tructure. The second con- sists of the physical nodes, which perform the various functions required to terminate the radio interface and to support the telecommunication services requirements of the users. The rest of the sub-domains are defined in Table 3.1. Figure 3.16 in Appendix A illustrates the four (Application, Home, Serving, and Trans- port) strata. It also shows the integrated UMTS functional flow, i.e. the interactions be- tween the USIM, MT/ME, Access Network, Serving Network and Home Network do- mains, including interactions between TE, MT, Access Network, Serving Network, Transit Network domains and the Remote Party. Table 3.1 The UMTS Architecture Domains USER EQUIPMENT DOMAINS: dual mode and multi-mode handsets, removable smart cards, etc. Mobile Equipment Consists of: (ME) domain The Mobile Termination (MT) entity performing the radio trans- mission and related functions, and the Terminal Equipment (TE) entity containing the end-to-end ap- plication, (e.g. a laptop connected to a handset). USIM domain The User Services Identity Modulo (USIM) domain contains data and procedures to unambiguously and securely identify itself, (e.g. smart card) INFRASTRUCTURE DOMAINS Access Network Consists of the physical entities managing the access network resources (AN) domain and provides the users with mechanisms to access the core network Core Network Consists of the physical entities providing support for the network fea- (CN) domain tures and telecommunication services; e.g. management of user location information, control of network features and services, switching and transmission mechanisms for signalling and for user generated informa- tion. It includes: Serving Network (SN) domain representing the core network func- tions local to the user's access point and thus their location changes when the user moves. Home Network (HN) domain representing the core functions con- ducted at a permanent location regardless of the user's access point. The USIM is related by subscription to the HN. Transit Network (TN) 