PZ and takes appropriate action should faults occur. The applications through a system wide concept of open ended modu- MAS functions can be divided as follows: larity. Telecom operators request services to be tailored to their individ- 1. Supervision for detection of occurred faults. ual needs and require some degree of control over the services. The 2. Tasks after fault detection to limit the effect of a fault and to opportunities for creating new sources of revenue for operators localise it. seems tremendous. Successful exploitation of these new oppor- 3. Repairs, including methods and aids to execute repairs with tunities will depend on getting new services to market very quickly. minimum disturbance. 4. Support for CP hardware extension. 32.10.1 The residential network Finally there are four subsystems designated for input/output In the residential network AXE can be used for: functions. To relieve the central processor, input/output functions are carried out by a support processing system connected to the 1. Local exchanges for metropolitan areas, towns and rural areas. central processor. 2. Remote subscriber switches. The Support Processor Subsystem, SPS, contains the above men- 3. Local (tandem) and national transit exchanges. tioned support processing system. It is built up of one or several general purpose type processors that can be configurated in a modu- AXE local exchanges comprise a variety of subscriber services. lar way, from small to large configurations, depending on capacity Typical services are abbreviated dialling and hot line, multi party and reliability requirements. conference, call transfer, call barring etc. The Data Communication Subsystem, DCS, consists of support processor software for data communication. It provides various 32.10.2 The business communication network kinds of data communication facilities supporting remote operation and maintenance, transfer of charging and accounting data to a The different activities within large organisations are normally remote or local facility 