We elaborate here how the "internals" of the evolved 3GPP system work. We stick to the most natural order, so that it becomes visible how single, smaller steps realize these main procedures:
- access control (authentication and authorization),
- node selection sunctions,
- IP address allocation and configuration,
- initial attachment and detachment,
- intra and inter system mobility (idle and active mode),
- session handling,
- specialized procedures (ANDSF communication, service continuity, CS fallback, warning message delivery), and
- procedures for I-WLAN mobility.
Note that this chapter provides explanations on functional level. The names of procedures and messages presented here may deviate from the actual names of protocol messages.