trex Figure 8.13 IP-PBX is located at the CPE (not shown) or outsourced as operator located and managed, or as an IP-Centrex Another IP voice solution is related to the backbone network: voice trunking, defined in Appendix 3, Objectives. The operator might also take care of modem traffic in the PLMN/PSTN/ISDN by means of NAS connections (Case 8). This is called Internet offload or data offload and is also defined in Appendix 3, Objectives. WLAN traffic (Case 2) and xDSL IP traffic (Case 4 and 6) might be connected with or without IP telephony. The expansion into voice traffic requires equipment such as gatekeepers and voice gateways. In fact, the development could end up in the target network with IP multimedia. See Figure 8.14. The WLAN operation for Internet and intranet access (Case 2) can also expand or integrate with other networks, such as 3 G. See Chapter 15. The incumbent (fixed) operator (Case 3) has clear ambitions and possibilities to offer all types of services in the list. It is true that for example MMS is seen as a mobile service, but the fixed network has a long tradition in messaging. The incumbent operator has for some time been in the forefront regarding migration of the backbone to packet mode (IP, ATM, MPLS). Considering that voice is the main service, a telephony server (TeS in Figure 8.14) is a key component in the network. An example of a migration scenario is given in Appendix 3. The xDSL solutions (Case 4) may be based on ATM or IP as transfer mode. They will be connected to the packet backbone accordingly. The mobile development (Case 5) has already been touched on in Figures 8.8-8.10. The focus is cost efficiency with the introduction of 3 G networks. Case 6 shows a home network. An example is shown in Chapter 10. Understanding Changing Telecommunications Building a Successful Telecom Business Other operator's network PBX (IP) Telephony IP/MM com server server Multi-service network IP QoS DSLAM EDGE node ISP/ASP/CSP VGW = Voice gateway Ethernet NAS = Network access server switch ER = E