f the users of today is illustrated in Figure 2.3, which shows the relationship between the end user and (one) retailer/service provider/operator. In this section the word retailer will be used for the end-user counterpart. Figure 2.3 shows that a growing number of offered services will ultimately be carried by a shrinking number of networks. For example, more and more services will be IP based. Mobility offers added value and mobile (or at least wireless) accesses will conquer an increasing part of the overall number of calls (including data calls). The fact that users in Europe during 2002 sent more SMS (short message service) messages than e-mails supports this statement. Traditional Subscriber Network Services Today Networks Users Services Services Network Users Figure 2.3 Power of the user End-User Needs and Demands In addition to the illustrated change, the end user can easily change retailer, making his position even stronger. These changes lead to a faster, less controllable and less predictable development than what was previously the case. 'Churn' is a key word, indicating the degree of subscriber movements from one operator to another. The fact that the end user is the main (final) financing source for telecom development gives a further dimension of user power. It also explains the increasing interest in the development of average revenue per user (ARPU) for various user segments. In general the expense patterns for needs such as food, entertainment and communication have been fairly stable. ARPU is further dealt with in Chapter 4. Figure 2.3 shows another way to describe the new power of the user. With many operators there is also churn between parallel networks. The development towards a technically unified single network is maybe a vision. Today we are in the middle of an unparalleled transitional period. Although the increas- ing abundance of possible services contributes to end-user power, it also creates uncer- tainty. A main reason for this is the (virtual?) unpredictability of the user. A good