e obvious savings in cabling and overall operation costs. The access systems for mobile and fixed telephony can quite easily carry multiple mode solutions, such as voice in circuit mode over ADSL combined with data in packet mode over IP (or ATM) over ADSL. A corresponding situation prevails for different releases in UMTS. The conclusion is that it is a matter of finding an economically comfortable conversion pace towards an assumed 'all-IP access'. Also QoS and security are important access issues. See Figure 13.6. The development is supported by the operating systems in the computers that take on more and more network-oriented tasks, also in QoS and security. Understanding Changing Telecommunications - Building a Successful Telecom Business Interior nodes BSC/RNC station Radio access network (RAN) Core network Diffserv domain Mobile Tunnels IP core QoS and security architecture Edge nodes Figure 13.6 All IP solutions require security and QoS in the access network, such as tunnels and Diffserv respectively 13.3.2 THE SUBSCRIBERS The subscribers can of course be segmented in many ways, such as residential users, mobile users, appliances, small and medium size enterprises, corporate regional, national or global enterprises with considerable intra-company traffic, and SO on. See Chapter 2. Lately the expression 'hot spot' has become common, since specific solutions target this segment. Examples of hot spots are found in Figure 13.7. A somewhat related segmentation differentiates between rural, suburban and urban subscribers. A metropolitan area is a common description of large cities. Regarding Figures 13.7 and 13.8, 3G/EDGE and WLAN etc are just examples of a number of possible solutions. See Figure 13.8. Airport Local area Hotel & Roaming Conference Office Office Public Hotel space Wide area Figure 13.7 Example of hot spots Access Network Mature GSM operators going WCDMA EDGE used as a complement to WCDMA Service continuity Seamless network Business aspects for rural areas WCDMA GSM/GPRS Sub-urban Sub-urban Urban