s a good rule that is applicable on the expensive access network. If the investments are much ahead of the related revenue much equipment (and capital) is Telecom Business poorly utilized. See the example on GSM radio access investments in Figures 4.51 and 4.52. A fairly modest over-investment may result in a prolongation of the payback time of half a year. Reusing Existing Investments For discretionary investments targeting an increased bandwidth the cost-efficient opera- tor might adopt this approach: 'A successful communications provider needs a stepwise approach in building cost-efficient broadband multi-service access networks that cater for Cumulative no. of RBS sites Over-investments Balanced investments Case 2 Case 1 Figure 4.51 Example of various strategies for access network investments The cellular race requiring a well-balanced investment plan: an example including two scenarios Accumulated operating income 700000 600000 Over-investment 500000 400000 300000 Case 2 Balanced investmentse 200000 Case 1 100000 Years of payback -100000 time (crossing zero) -200000 Figure 4.52 Example of various strategies for access network investments Understanding Changing Telecommunications - Building a Successful Telecom Business the new demands of end users while at the same time reusing existing investments and securing new revenues'. This approach fits extremely well in the case of established access operators with investments in copper, masts etc. The best example today is perhaps implementing 3G mobile systems with maximum reuse of 2G investments. See Figure 4.53. Convergence Fixed Mobile in the Access Network: Network Sharing Cost-efficiency optimization includes expenditure from leasing or renting capacity from other operators. A new operator relationship is called 'network sharing'. This is a way to reduce CAPEX by means of radio access sharing or geographical area sharing, introduced by UMTS operators. Lower radio access network Common network Site sharing management GSM RBS/ WCDMA RBS Service network/ Combine