 phenomenon is shown in Figure 2.1. In this figure, the average traffic per day and per active user line in the United States is represented in terms of bit/s/line. Reported on a day (24h), the traffic of 11 bit/s/line rep- resents an average time of about 2.5 min/day at a transmission speed of 64 kbit/s. Average user traffic/day Internet-driven traffic level Transport capacity Transport systems capacity 2.4 Tbit/s 100 bit/s/line Internet 1.2 Tbit/s revolution Pre-Internet 320 Gbit/s average 11.1 bit/s/line 20 Gbit/s 10 Gbit/s 2.5 Gbit/s FIGURE 2.1 Average traffic per day and per active user line in the United States is in bit/s. As an example, reported on a day (24h), the traffic of 11 bit/s represents an average time of about 2.5 min at a transmission speed of 64 kbit/s. (After Iannone, E., Personal Elaboration of Ovum "Capex Conundrum" report, Ovum, s.l., 2003.) Drivers for Telecommunication Network Evolution From now on, for simplicity, we will refer to 64kbit/s as the telephone standard bit rate. All the discussions are easily adapted to the cases in which the standard bit rate was dif- ferent, for example, 56 kbit/s. In conclusion, the average traffic in the pre-Internet era was constituted by 2.5 min of phone calls per day per active line. At the end of the analyzed period (2001-2002), the traffic increased at about 25 min of phone calls per day per active line. Of course, this increase was not due to the fact that the average person increased the duration of the phone calls by a factor 10, but the fact that the phone line was used via the dial-up connection also to browse the Internet. From Figure 2.1, it is also clear that the traffic curve almost saturates, due to the fact that the average person tends to limit his or her use of the Internet if only the dial-up connec- tion is available. Thus, in order to completely unfold the potentiality of the Internet, it was needed to provide the user with a greater capacity access line. Figure 2.1 also reports the evolution of the capacity of the most advanced com