 utilises IP networking as much as possible (Figure 4.9). Therefore this goal has been given the name of an 'all-IP' Network Evolution network. IP will be used in both the network control and user data-flows. The mobile network implemented according to the 3GPP release 5 specifications will be an end-to-end packet switched cellular network using IP as the transport protocol instead of CCS7 (common channel signalling 7), which holds a major position in existing circuit switched networks. The IP based network will still support circuit switched services. The 3GPP release 4/5 networks will also start to utilise the possibility of using new radio access techniques. In the 3GPP release 99 network the basis for the UMTS terrestrial access network (UTRAN) is WCDMA radio access. In the 3GPP release 4/5 networks another radio access technology derived from GSM with enhanced data for GSM evolution (EDGE) will be specified to create the GSM/EDGE radio access network (GERAN) as an alternative to the UMTS mobile network. In the 3GPP release 5 network the access network will experience more changes, with the changes done in the core network being minor by nature. In the 3GPP release 5 network the traffic is always packet switched and may be either real-time or non-real-time. In the development of release 5 the focus has shifted to the PS domain, which has been extended with the IMS functionality. The services, their accessibility and creation are emphasised in the 3GPP release 4/5 core network implementation. The service capability layer has already been introduced in the 3GPP release 99 network but in further implementations its role will be increased by open service architecture (OSA) based solutions. The OSA provides mechanisms for universal service creation and management. The changes performed between release 4 and release 5 should not be visible to the end users. The UTRAN radio path still works in the same way and the terminals being used are also still working. Within the access network, however, the transport technolo