d fixed lines to support demand from computer users for data communications via packet switched networks (originally CCITT-X25 with variations such as X32, frame relay and increasingly TCP/IP) although digitised voice remained as a circuit switched service. A new generation of digital network, the Integrated Services Digital Network (ISDN), was launched across OECD countries from 1985 onwards. ISDN line speed standards of 64 kbps and 2 Mbps E-1 lines in Europe set new performance achievements in the local loop (with 56 kbps and 1.5 Mbps T1 lines in the United States) and end-to-end digital technology. This produced some major functional advances, such as Centrex, and a richer set of customer services. Features were introduced either through the handset instrument or the local switch offering voice messaging, call forwarding, recall last number dialed, short dialling, etc., collectively termed CLASS services (Custom Local Area Signalling Services in the Bellcore nomenclature). The arrival of fibre optics moved data rates over long distance from hundreds of kilobits per second in the late 1970s towards links at up to a terabit per second from 2000 onwards, an increase of ten million times in capacity. Taking a high quality (16 kbps) duplex voice channel, a one terabit cable can carry over 62 million voice conversations - sufficient for everyone in France to speak with someone in the United Kingdom at the same time. However the pace of infrastructure digitalisation was highly variable even for OECD countries, as shown in the table below for 1990. Table 2.A1.1. Degree (%) of digitalisation of the telephone network by 1990 in selected OECD countries Transmission Local switching Long distance switching France Germany United Kingdom Sweden Greece Netherlands Spain Source: OECD, Telecommunication Network-based Services: Policy Implications, ICCP-18, 1989; CEPT, CEC, OECD. As shown in Table 2.A1.2, also there were considerable variations among some leading companies as to the extent and pace of digitalisation. Many countr