SDPs are involved in processing a call. Multimedia services require IN support when multiple calls are involved in a service. Thus, in the long term, dis- tributed intelligence both in the core network and also in peripheral devices, will be basic to providing services. 16 The SCP provides run-time functionality for intelligent network services. When an exchange needs to process an intelligent network call, it passes control of that call to an SCP via the SS7 network. The SCP runs the service required by the call and returns call routing and call state information back to the exchange to process the call. SNs and CSNs handle tasks such as voice announcements and dual-tone multi- frequency (DTMF) decoding. Intelligent network services are created by service developers using the SCE. This can be regarded as the communications service anal- ogy to integrated development environments (IDEs), which are used by software developers. The SCE is used to design and develop the executable files and custom database for the service, and these tasks are collectively referred to as "implementa- tion" of the service.1 The implementation of a service is installed on an SCP to be run and is also installed on the service management system in order to send provisioning requests to the SCP databases. The service management system is used to provision and Alcatel has a strong history in developing IN infrastructure. Incidentally, Clarity International's VP of R&D (Dr Steve Parry) was a senior manager in Alcatel's IN group before he joined Clarity. Many senior people in successful OSS vendors had a significant career in the telecom industry before moving to a pure OSS vendor. 16 The Telecommunications Information Networking Architecture (TINA) is an open standard intended to support services based on distributed computing. 17 The ability to use software to design and implement services with almost infinite variations has spawned the new field of telecom service engineering. Important work has been done in this area at the Telecommunica