ocess the data received from distributed software agents and reduce the manual effort involved in fault localisation, diagnosis and correction. OSS for Telecom Networks Workstation Network cloud with distributed operation and maintenance Workstation Workstation Workstation Figure 2.2 Distributed operations and maintenance functionality. OSS at network operations centre (NOC) Network cloud Figure 2.3 Centralised operational management. In the past, O&M was decentralised, and many operators still prefer this (Figure 2.2). The bulk of an operator's costs are involved in O&M work. Associated costs include staff, decentralised and duplicated facilities and redundancy ("overdimensioning") in the network. Overdimensioning is the surest but most expensive way to ensure a high grade of service. In addition, owing to the large amount of expertise needed to main- tain a network because of the usually vast variety of types and makes of equipment in the network, staff costs for O&M are high. Unfortunately, decentralising involves resource duplication, added costs and inefficiencies in communicating with staff. An OSS of today can control and supervise several sets of network equipment in a centralised management model (Figure 2.3). Some telecom professionals broaden the term OSS to include billing systems and customer relationship management (CRM) software, although billing and CRM are beyond the scope of this book (Figure 2.4). 2 Network Management OSS Overview Sales and CRM system Network Figure 2.4 Customer management. Centralised operational management by an OSS has many business advantages for a service provider. Many functions can be efficiently handled from just a handful of locations so that fewer staff are needed. Although the advent of OSS systems allowed centralisation. The benefits of centralised operational management have induced many com- panies in the telecom industry to invest in OSS software. Several industry confer- ences are devoted to industry-wide collaboration for improving OSS. OSS industry bodies, in 