ment systems that allow rapid creation and modi- fication of end-to-end network services that are integrated with their business management functions. The TMN management architecture model of the ITU-T breaks down the activities associated with managing a telecom network by defining functional blocks and interfaces between those blocks. Network hardware sold by equipment vendors is accompanied by a network ele- ment management system (EMS). To allow integration, the EMS must implement a (preferably open) northbound API that allows the service provisioning, fault and performance monitoring functions to be accessed from network and service man- agement applications. To achieve support for the many operating system platforms and languages that are used to develop applications, the OMG developed CORBA, which allows distributed applications to communicate with each other in a platform- and language-independent way. Using CORBA to define the interfaces between the layers of the TMN model, carriers can integrate the applications and functions pro- vided by the EMS. When provisioning a new service, the carrier or service provider enters a contract with the customer to ensure that the service delivered meets a defined set of service level metrics. 14 This contract is embodied in the SLA, which includes metrics such as availability, latency (delay) and loss. In order to report on these and other para- meters, the equipment and EMS must collect, store and present accurate statistics that can be used to define the terms of the SLA. This data must reliably be collected for each managed element within the EMS domain, and be made accessible to external reporting and billing applications. 6.3 Service Management in the Intelligent Network The intelligent network (IN) is a way of implementing services in the main telecom network (the public switched telephone network, PSTN) using instructions and data in computing equipment that is remote from the exchanges. The computing 12 They were fairly successful, although a little ahead of 