Private Telecommunication Networks (PTNs), as described in Technical Report ECMA TR/57, provide services to their users based on the services provided to users of public ISDNs and described in the I.200 series of Recommendations from CCITT.
Whilst basic services (bearer services and teleservices) available to users of public ISDNs are generally available in the same form to users of PTNs, the situation with supplementary services is more complicated:
- PTNs offer some supplementary services which are not generally available to users of public ISDNs;
- a few public ISDN supplementary services are not applicable to PTNs;
- some supplementary services available to users of public ISDNs are available in a modified form to users of PTNs.
This Ecma Technical Report therefore contains brief descriptions of supplementary services typically offered by PTNs, some of which are currently undergoing standardization. Relationships with corresponding standardized services in public ISDNs are also described, where applicable.
Ecma International uses the term Additional Network Feature (ANF) to describe certain features which cannot correctly be described as supplementary services but, like supplementary services, enhance the control of basic services. Whilst a supplementary service is made available to individual users for the direct benefit of those users, an ANF operates autonomously within a PTN and enhances the operation of the PTN for the benefit of all users or of the PTN administration. This Technical Report also considers some ANFs.
The list of supplementary services and ANFs covered by this Technical Report is not intended to be exhaustive.
A special type of PTN user of importance is the attendant. This Technical Report also considers the special characteristics of attendants and the applicability of supplementary services to attendants.
The purpose of this Ecma Technical Report is to guide manufacturers of PTN equipment and operators of PTNs in the selection of supplementary services and ANFs to be made available. It can also act as a tool for identifying potential candidates for standardization, although the appearance of a supplementary service in this Technical Report does not imply that it should or will be standardized for PTNs. Where an Ecma Standard exists containing a service description for a supplementary service or ANF described in this Technical Report, the service description in that Standard should be regarded as correct in the event of conflict with the description in this Technical Report. Deviation from a description in this Technical Report may be found necessary during the more detailed investigations involved in the writing of a Standard.
The use of Computer-Supported Telecommunication Applications (CSTA) in the provision of supplementary services and ANFs is outside the scope of this Technical Report.