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 digital photos has started to increase. Traffic in the interactive class has higher priority in scheduling than background class traffic, SO background applications use transmission resources only when interactive appli- cations do not need them. 5.4.5 TRANSACTIONAL CLASS Transactional means financial transactions B2B and B2C where security and information accuracy are crucial. 'Micro payments' for parking and cinema tickets must be possible. Transaction-based services have caught the interest of stakeholders who are eyeing business opportunities. The development depends a lot on trust and security. The mobile phone becomes a personal trusted device (PTD). Typical transaction-based services include supporting infrastructure services throughout the various stages of the service life-cycle, such as issuing the WAP identity modules (WIM), certificate authority (CA) services and payment-clearing services. Banks are strong players here. 5.4.6 MESSAGING CLASS Messaging can be integrated into the background class (or interactive class when inter- active). However, it is a revenue-wise important type of service and it requires special equipment. This cou