This Annex specifies the extensions required to the basic call control signalling protocol defined in the main body of this Recommendation to support calls within a Corporate telecommunications Network (CN) and to support calls which enter or exit the CN via Gateway PINX functionality performed by the public network. The protocol is applicable at the T reference points to which VPN services are provided. The support of these additional signalling capabilities is a network option. These DSS1 extensions are made available to PINXs on the basis of bilateral agreements at subscription time.
The additional basic call signalling capabilities identified in this Annex are to provide information flows that are functionally identical to the information flows provided by the PSS1 basic call control protocol (as defined by ISO/IEC 11572).
In the context of this Annex, the public network (providing VPN services) can be seen, from the private network perspective, as providing an interconnection between a PINX supporting DSS1 extensions for VPN and another PINX supporting PSS1 information flows. This second PINX may be a physical PINX connected to the public network or may be an emulation of an end PINX function provided by the public network.
An emulation of Originating PINX functionality by the public network should, as a minimum, meet the requirements of an Originating PINX Call Control as defined in ISO/IEC 11572 for the circuitswitched call control and the ISO supplementary services associated with the basic call (CLIP, CLIR, COLP, COLR, SUB). In addition, the Transit counter ANF (defined in ISO/IEC 15056) may be supported by these DSS1 extensions.
An emulation of Terminating PINX functionality by the public network should, as a minimum, meet the requirements of a Terminating PINX Call Control as defined in ISO/IEC 11572 for the circuitswitched call control and the ISO supplementary services associated with the basic call (CLIP, CLIR, COLP, COLR, SUB). In addition, the Transit counter ANF (defined in ISO/IEC 15056) may be supported by these DSS1 extensions.
An emulation of Transit PINX functionality by the public network should, as a minimum, meet the requirements of a Transit PINX Call Control as defined in ISO/IEC 11572 for the circuit-switched call control and the ISO supplementary services associated with the basic call (CLIP, CLIR, COLP, COLR, SUB). In addition, the Transit counter ANF (defined in ISO/IEC 15056) may be supported by these DSS1 extensions.
A Relay Node in a VPN includes the following functions:
– minimal routing capability;
– transparent handling of private networking information (e.g. transit counter).
An emulation of Incoming Gateway PINX functionality by the public network should, as a minimum, meet the requirements of an Incoming Gateway PINX Call Control as defined in ISO/IEC 11572 for the circuit-switched call control and the ISO supplementary services associated with the basic call (CLIP, CLIR, COLP, COLR, SUB). In addition, the Transit counter ANF (defined in ISO/IEC 15056) may be supported by these DSS1 extensions.
An emulation of Outgoing Gateway PINX functionality by the public network should, as a minimum, meet the requirements of an Outgoing Gateway PINX Call Control as defined in ISO/IEC 11572 for the circuit-switched call control and the ISO supplementary services associated with the basic call (CLIP, CLIR, COLP, COLR, SUB). In addition, the Transit counter ANF (defined in ISO/IEC 15056) may be supported by these DSS1 extensions.
The attached PINX acts as the user within the DSS1 protocol defined by this Annex.