ations system components. This also interacts with the company di- rectory which is updated automatically as moves and changes are made in the system. The Telecom Handbook * 127 CALL ACCOUNTING & TELEMANAGEMENT SYSTEMS Cost Accounting/Allocation/Chargeback This is usually the first application that is implemented. Cost allocation has the objective of providing cost center management with meaningful information about the telecommunications ex- penses, facilitating the exercise of local management prerogatives to control expenses. This is accomplished by (1) providing detailed reports to up- per management, (2) summarizing telecommunication costs for all levels of management and (3) providing journal entries or financial summary information as input to existing corporate fi- nancial control systems, such as the general ledger. This permits a review of these expenses in conjunction with normal planning and budgeting activities. Directory Systems Directory systems' objective is maintaining and making avail- able accurate telephone and e-mail directory information. They support three directory functions: directory assistance, directory publishing and directory updating. The assistance and publish- ing functions are generally straightforward. The most complex part is the updating and maintenance activity. Information for the directory comes not only from telecommunications, but also from the Human Resources and Information Technology Depart- ments. Network Engineering Systems Changes in tariffs and the continual introduction of new ser- vices with varying costs create the need to engineer and re-engineer your communications facilities (circuits) for both voice and data communications, including Internet access. Net- work Engineering support systems fall into two categories: data reduction and simulation. Data reduction is a method whereby detailed usage information is processed and reduced to summary 128 * The Telecom Handbook CHAPTER 6 form. Reports that reflect the pattern of calls (e.g., all calls to a particular ar