hould be calculated, e.g. using a traditional net present value (NPV) method. The method is explained in Appendix 2. While the marginal investments are difficult enough to estimate, the revenue calculations are really hard to perform. There are a number of aspects that directly or indirectly impact the revenues. When an end user chooses to subscribe to a particular service delivered by a specific service provider, the choice is not only based on a simple price comparison. Quality and timeliness are equally important factors. There is always a risk of losing the customer to a competitor, which may result in lost revenues from other existing services, which this customer would have used. The effects in monetary terms when introducing new services are normally: new rev- enues, increased revenues of existing services, savings, but also new costs, increased costs and investment costs. A specific case of revenue and savings impact would be the introduction of voice over IP (VoIP). Savings would be possible especially in the long- distance network, when replacing existing technologies with a higher operating cost. On the revenue side, however, VoIP can have a cannibalization effect in direct competition with an own higher charged conventional telephony service. The business case is a basis for: achieving a uniform corporate approach to investment analysis ensuring formal documentation of assumptions comparing alternative investment proposals setting investment priorities The content is implied by the policy and includes: key issues financial analysis 4.5.3 TOOL: SIMPLIFIED OPERATOR PROCESS PLANS Operator process plans can be used for business purposes. One example is to compare two or more technical solutions by comparing the impact on the processes. See Figure 4.33. The view is used in Section 4.7. Among the ingredients of a business plan are a service plan and a technology plan. The services in the service plan are supposed to support the ROCE in the best possible way, and the technology or service implementation plan