Bjørn Løken
With mobile telephone systems like NMT we have become familiar with the flexibility and ease of use of automatic roaming. With automatic roaming the subscribers can access the network where they happen to be at the time of call. An exchange in a mobile network must therefore be able to serve any subscriber entering its service area.
Such flexible service handling is not possible in existing fixed networks because call control for a subscriber is permanently associated with a particular exchange, i.e. the exchange where his subscriber line terminates. However, one of the near term targets of service development is to extend mobility to fixed networks by introducing personal mobility.
The introduction of mobile services has necessitated a change in traditional network design. In order for an exchange to give services to all roaming subscribers, subscriber data must be easily retrievable from sources external to the exchanges. This leads to the requirement that call control and subscriber data must be functionally separated. In systems with personal mobility also the service itself must be executed in separate network nodes.
Services such as advanced freephone, televoting, credit card calling and virtual private networks will impose similar requirements on the network architecture. This enhanced architecture is called Intelligent Network (IN).
The original idea behind IN was that certain services were more efficiently implemented by allocating part of the service execution to separate network entities (Service Control Point). For other services this was the only way in which they could be implemented. One important point is that mobility and IN represent two routes towards the same type of network architecture.
An implementation of a network where a separation between call control, service control and user data is introduced requires the support of a signalling system capable of supporting real time transaction oriented exchange of information between network nodes dedicated to switching, data storage and service processing.
The transaction Capabilities Application Part (TCAP) of Signalling System No. 7 has been developed for meeting these requirements. It is also the first step towards a vendor independent application layer interface between network entities.
In order to obtain harmonised IN services internationally standards must be developed. A first set of such standards will be put forward to the CCITT Plenary Assembly in 1993 for adoption as the Q.1200 series of Recommendations. The Q.1200 series includes network architecture, a set of capabilities or building blocks for service creation and allocation of functions to physical entities with associated protocols. These protocols are the second step towards a vendor independent interface.
Looking at the way this international work on IN has taken one may say that IN is not a specific technology but rather a methodology for future network development. Intelligence in the network means that services are separated from basic switching and transmission.
When IN has been fully developed, it will offer several benefits to all parties involved: network operators, service providers, service subscribers and users. Some of these are:
In order to exploit the benefits much research is required on methods and tools for
Efficient solutions in these areas will be an important element in an environment where network operators are competing for gaining market shares. Those who can deliver what the users need at the right time at an acceptable price will be the market winners. IN evolution is thus one important strategic element for network providers in the future. Many network operators are beginning to see this and are, therefore, putting much resources into IN research. Since this research is expensive and requires much resources, several network operators have joined forces, for example in EURESCOM and RACE, even though they may become competitors in the future. Most of them expect to gain more from cooperation in research than they may eventually loose from competition. Norwegian Telecom is also participating in this work. The advantages for us is that, being a small network operator, we gain access to results that we otherwise could not afford to produce on our own.
The research will also determine the direction in which IN standards develop and will in the long run replace the proprietary standards the network operators are forced to buy from industry today.