problem management plays a key role. Some of the operations involved in service assurance need support from the element management system. Let us consider the EMS functionalities involved in service assurance: When a trouble occurs in the delivered service, this would be associated with the occurrence of some event on a resource. At the service management level, an event is generated notifying the disruption of service. This is followed by an event trigger to automatically fix the trouble condition or a notification/ assignment of work to a technician for looking into the issue and fixing it. A service level log/alarm will not be of much help to the technician. The log/alarm generated on the resource that caused disruption of service and displayed by the fault management system in the EMS would be the most precise fault notification with maximum information for the technician to fix the issue. For example, if there was a loss of service when a set of patches (bug fixes) were installed on a network element, then the exact patch that caused the network element to malfunction can be selected and removed. This helps fast restoration of service to meet SLA. As already discussed, performance management reports generated on the ele- ment management system is a key input on QoS. The periodic performance records collected on quality metrics and key parameters characterize the per- formance of the network resources over service intervals. Performance man- agement also has functionality to set thresholds on specific parameters. The EMS generates events when thresholds are crossed, which helps to identify trouble scenarios before they arise and hence actions can be taken that would guarantee the commitments on service assurance specified in SLA. Customer support is also at times bundled with service subscription. There would be specific guidelines on the duration to complete a customer request. It could be setting up a service, fixing a trouble condition or answering a query. Good customer support is a key differentiating fa