service
- In OSI terminology, a service is a collection of functions of a layer that the layer offers to a higher- level layer at the so-called service access point. A service is always offered to the directly superordinate layer. The services of the individual layers are characterized by the different tasks of these layers. Thus, there are network services on the network layer, transport services on the transportlayer, and application services on the applicationlayer.
- The International Telecommunication Union( ITU) designates carrier services for transport and teleservices for application. These standardized teleservices are provided by network operators. Teleservices include fax, teletex, and telephone, among others.
- Services in the telephone network that extend the basic function of the telephone service are called supplementary services. Such supplementary services, which are also referred to as service features, can include call forwarding, call waiting, call forwarding, and others.
- In the security architecture, there are the security services for defense against attacks. These security services, which include confidentiality, integrity, authentication, access control and irrevocability, are realized by security mechanisms.