ntory would be placed at different locations and the quantity of each of Fundamentals of EMS, NMS and OSS/BSS these elements may be different at each of the locations. Again some of these elements may be faulty and some of the working elements might be already in use, booked for a specific provisioning, being fixed, and under maintenance leading to a different status at a given point of time. When the provisioning module needs resources based on parameters like status, location, capacity, and SO on, a decision is made on the most appropriate resources to be used. This information is provided by an inven- tory management module. The inventory data can also include details on serial number, warranty dates, item cost, date the element was assigned, and even the maintenance cost. All inventory information is logically grouped in the inventory management module. This makes it easy to view and gener- ate reports on the inventory. Capacity planning can be performed based on inventory data and new inventory can be procured as per need before an outage occurs. Inventory affects the CAPEX and OPEX directly and hence inventory reports are of much importance to senior management. Procuring inventory from a new vendor usually goes through a rigorous vendor analysis followed by legal agreements for license including maintenance and support. Billing: Records are generated by the elements in the network that can be used for billing. In switches where calls are handled, call details records (CDR) are generated that have billing information. CDRs can have multiple call records. The CDR is parsed to for parameters like calling party number, destination number, duration of call, and SO on, and the customer is billed. A mediation module performs the activity of parsing and converting the infor- mation in CDR to a format that can be used by the billing system. Billing modules have a rating engine that applies the tariff, discounts and adjust- ments agreed upon in the SLA as applicable, and create a rated record on how the bill was cal