historical data and correlation of current data, the service provider can determine how degradation in network performance at the optical layer affects customer services. 6.5 Real-time Service Controls Real-time service controls are most relevant in the potentially dynamic area of broadband mobile/wireless services and, in particular, broadband mobile IP services. OSS for Telecom Networks This is because broadband mobile IP lends itself to innovative services driven by unique marketing imperatives, which have been well publicised in the telecom industry press. It is still early days for mobile IP services in that operators are only now learning what drives revenue in this domain. Therefore, service providers realise that they must spread a wide net by offering a variety of services in order to appeal to a variety of (potential) desires of (potential) customers. 19 At the same time, it is necessary to build flexibility into service offerings, create and enforce value-based billing models and track and measure usage. The market for IP services is dynamic, partly because it is new and partly because it is not well understood by either service providers or consumers or enterprise customers. Thus, an IP service provider's business infrastructure must be able to adapt to the dynamism in the value attributed to each IP service as consumers are found to be enthusiastic or not so enthusiastic about innovative service offerings. This need to support dynamism is a challenge. Potential solutions are: 1. Agent-based billing software which uses a decentralised architecture, with con- tent providers establishing separate data links to the service provider's central billing system. These systems receive access requests, validate access and then bill for services sequentially but not in real time. Software developers must inte- grate applications and content services into the billing software using APIs. 2. Real-time service control systems which unify system policies, customer access profiles and billing information on a central