bile ser- vices. After the introduction of GSM in 1991, the success of digital mobile telephony in Europe was SO big to justify the huge CAPEX needed to deploy a continental network covering almost all the populated areas and with easy roaming among all the relevant carriers [12]. However, up to the present time, mobile and fixed-line services are considered by end customers as separate products, and the success of mobile services does not have a posi- tive influence on fixed-line revenue. Moreover, after a long period of growth, the mobile market started to slow down after 2005. This effect is shown in Figure 2.4, where the global revenues and CAPEX for telecom carriers are shown versus time from 2006 to 2010 (where the 2008-2010 figures are fore- casts) [11]. The average yearly growth rate is about 2%, quite low taking into account that it is posi- tively affected both by the weakness of the U.S. dollar with respect to the euro and the yen and by the mobile revenues that, in the considered period, are still growing faster than those related to fixed services. As far as CAPEX is concerned, it is almost constant, a further proof of the state of stagna- tion of the fixed-line telecom market. Due to these trends, the market of fixed-line services started to experience a struc- tural state of crisis, mainly due to the imbalance between the investment and running costs needed to set up and maintain an up-to-date telecommunication network, and the amount of revenues related to service delivery. This condition is worsened by the fact that many carriers have a high debt that makes it difficult to carry out CAPEX-intensive operations. Drivers for Telecommunication Network Evolution Trillion U.S. dollars Revenues (T$) CAPEX (T$) FIGURE 2.4 Global revenues and CAPEX for telecom carriers in trillion dollars versus time. (After Saadat, A., Service Providers Capex, Opex, ARPU and Subscribers Worldwide, Infonetics, s.l., 2007.) Exceptions are carriers in emerging nations like China, where the market is more dynamic due to the 