is indicated in Chapter 1, Section 1.3. Access Network Some internet access possibilities AS = (Internet) Access server PSTN/ISDN PSTN/ISDN PSTN/ISDN "2B1Q + PSTN" DECT (PCS) PLMN (PCS) ADSL (PSTN/ISDN) Public IP network + SATELL (core) U.S. etc. (PSTN/ISDN) DATA, VOICE, VIDEO VOICE + CABLE MODEM "BUSINESS" VIDEO REQUIRE "BUSINESS" SERVICE FO. Cu VIDEO, VOICE, DISCRIMINATION (QoS) "BUSINESS" LAN INTERC. WIRELES Figure Internet access over all accesses quickly became the a top issue in the 1990s Some support for an improved business case has been covered in previous chapters: Chapter 4: Re-using existing investments. Convergence fixed-mobile access. Network sharing. Chapter 5: 'Service continuity' over different systems. Stepwise extensions. The fact that voice and data have quite different network requirements has been reflected by dedicated access system developments. However, since access is the most expensive part of the network, the interest in integrated access solutions has been substantial. Inte- gration attempts include finding common transmission as well as common transfer mode. Circuit-switched data technologies (X.21) and several packet switched voice trials testify to the ambitions. The success of the circuit and packet solutions as final integrated solu- tions was initially limited and a cell-switched mode (ATM) was tested as a compromise. However, it was the IP packet technology that became part of all computers, thus becom- ing the strongest access standard at the network layer, with Ethernet as the strongest link layer technology. With voice becoming a minor part of the total traffic, and packet technology becoming the dominating transfer mode the question is if VoIP is the final solution for voice access? For an enterprise there are 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 correspond