With regard to the definition of the term “telecommunication” itself, the ITU has the following to say: “Any transmission, emission or reception of signs, signals, writing, images and sounds or intelligence of any nature by wire, radio, optical or other electromagnetic systems” (ITU, 2011). To enable this telecommunication capability, telephone companies provide telecommunication services. To quote (ITU-T T.174, 1996), telecommunication services are “that which is offered by an administration to its customers in order to satisfy a specific telecommunication requirement”. A more detailed definition is given in the words of (Calisti, 2003), where a telecommunication service is “a set of independent functions that are an integral part of one or more business processes. This functional set consists of the hardware and software components as well as the underlying communication medium. The customer sees both as an amalgamated unit. A service can be a service component of another service”. Another quite similar definition of the term is described by the 3GPP, a service is “a component of the portfolio of choices
2.3 Value-Added Services in NGN
offered by service providers to a user, a functionality offered to a user.” (3GPP TR 21.905, 2005).
Besides the provided definitions of the term “telecommunication service” or rather “service”, many others exist and the words are often used in several different contexts with somewhat different meanings although they are describing the same, such as in (Kühn, 1991), (ETSI TS 122 228, 2011), (ETSI TS 122 105, 2011), (ETSI TS 122 101, 2011) and (ITU-T I.211, 1993).
In principle, telecommunication services are divided into bearer services, teleservices and supplementary services.
A bearer service is a type of telecommunication service that provides the “capability of transmission of signals between access points” (ETSI TS 122 105, 2011). Typically, bearer services are categorised by their information transfer characteristics, methods of accessing the service, interworking requirements (also to other networks), and other general attributes (Harte et al., 1999). Bearer services cover the lower three layers of the OSI (Open Systems Interconnection) model from physical layer up to the network layer.
A teleservice is a type of telecommunication service that provides the “complete capability, including terminal equipment functions, for communication between users according to protocols established by agreement between network operators” (ETSI TS 122 105, 2011). The teleservices are user end-to-end services (e.g. telephone calls) and cover the full seven layers of the OSI protocol layer model.
Supplementary services modify or supplement basic telecommunication services. Therefore, they cannot be offered to a customer as a stand-alone service and must be
offered in combination with a basic bearer service or basic teleservice. The same supplementary service can be applicable for a number of telecommunication services (ETSI TS 122 105, 2011).
According to (ETSI TS 122 001, 2011) and (ITU-T I.210, 1993), Figure 2.8 illustrates the categorisation of telecommunication services.
Figure 2.8: Categorisation of telecommunication services
Besides the already mentioned classes of services in the telecommunication domain, a further service type, value-added (telecommunication) services, exists. According to (ETSI TS 122 101, 2011), these value-added services can be based on fully proprietary protocols or standardised protocols. With regard to this research work, the following definitions of the term “value-added services” might be suitable. The OMA (Open Mobile Alliance), for instance, defines in (OMA ORG, 2007) that the term stands for a “telecommunication/information service that is offered in addition to and/or in conjunction with a basic telecommunication/data service”. This rather generic definition indicates that every service can be seen as a value-added service if it extends the functionality of a pre-existing basic telecommunication service.
telecommunication services teleservice basic teleservice basic teleservice + supplementary service(s) bearer service
basic bearer service basic bearer service + supplementary service(s)
2.3 Value-Added Services in NGN
(Glitho et al., 2003) agrees with the OMA. In their opinion, value-added services are “defined as anything that goes beyond two-party voice calls” (Glitho et al., 2003). Furthermore, “Value-added services are usually grouped under two umbrellas: telephony services and nontelephony services. Telephony services interact with call control while nontelephony services do not” (Glitho et al., 2003). The authors also give examples of telephony services such as conferencing, call diversion or telephone voting. Nontelephony services can be special instant messaging services, push-to-talk and multimedia messaging.
A further definition of the term “value-added service” is given by (Guo et al., 2009) who point out that value-added services “add value to the standard service offering, spurring the subscribers to use their phone more and allowing the operator to drive up their ARPU (Average Revenue per User)” (Guo et al., 2009). They also state that “Both the academic and the industrial communities have paid much attention on the subject how to design and implement the personalized service and shorten the time to market” (Guo et al., 2009). Here, the authors denote the potential of value-added services, especially emphasising the economic benefits for service providers and network operators and the need for mechanisms in order to provide the services fast, custom-made and in high quality.
The most appropriate definition of value-added services relating to this research work is provided in (Lehmann, 2014): “Value-added Services (VAS) are functional properties which will offer certain comfort to consumers. Consumers will recognise additional benefit by value-added services”. Regarding the composition of value-added services, (Lehmann, 2014) discusses that they “are based on a combination of one or more bearer
services and one or more teleservices, and optionally, one or more supplementary services.” The author also states that value-added services can be an extension to basic teleservices and they can sometimes stand-alone (e.g. non-call related services). “VAS also have a certain time dimension associated with them. A value-added service today can become a basic service in the future when it becomes sufficiently common place and widely deployed, and for example, is no longer used as a differentiation feature among operators” (Lehmann, 2014). The author describes the positioning of value-added services within the telecommunication domain and predicts that the provisioning of them will play a major role for the operators in future.
As already mentioned in the sections 2.1 and 2.2.3, unlike basic telecommunication services being provided in the service stratum of the NGN by Call Servers, the value- added services are provided by Application Servers. According to (Trick and Weber, 2009), the handover of the service intelligence from the Call Servers to the Application Servers leads to a significantly low dependency between the network and the value-added services. This aspect makes it possible to quickly and easily provide new value-added services.