In accordance with Recommendation I.130 [1], the following three-level structure is used to describe the telecommunication services:
– Stage 1 is an overall service description, from the user’s standpoint;
– Stage 2 identifies the funcitonal capabilities and information flows needed to support the service described in stage 1;
– Stage 3 defines the signalling system protocols and switching functions needed to implement the service described in stage 1.
This Recommendation relates to stage 1 (overall service description) for the teleaction service in the ISDN.