rational systems and between operational and supervisory systems. Remote supervision including alarms is shown in Figure 5.9. A terminal module (with- out screen and buttons) sends information about status and position. The module can be placed in different machines and vehicles. The information will be presented in a mobile terminal or computer. A service technician takes care of appropriate actions. Data traffic applications such as e-mail delivery (including attachments), SMS, down- loading information from databases and reception of measurement records can be delivered background since such applications do not require immediate action. The delay may be seconds, tens of seconds or even minutes. Among background services are also: Telemetry. Corporate database access. This application is used for field services etc. Fleet management (couriers, trucking, taxi) including positioning. This service might be very common and bound to proliferate, for example in combination with vehicle navigation systems. Information push (news, financial data, sports, traffic, weather and SO on, possibly with positioning). Other non-real time services, for example DNS traffic, push/pull services, other mobile information services which are both commercial and society related and software down- loads of terminal properties. Background traffic is one of the classical data communication schemes that is broadly characterized by the fact that the destination is not expecting the data within a certain Network Alarm Operation & maintenance Database on household products Vehicle information Service alarm Figure 5.9 Example of remote supervision Services time. It is thus more or less insensitive to delivery time. Another characteristic is that the content of the packets does not need to be transparently (isochronously) transferred. Data to be transmitted have to be received error free. The electronic postcard is an example of a new application that is gradually becoming more and more common. The terminals have built-in cameras. Transfer of d