This Recommendation has been updated to include new capabilities and functionalities included in the IN CS‑2 series (Q.122x) of Recommendations. It provides a general architecture of the IN service plane in a way that specific functionalities and their interactions can be identified and described in other Recommendations which make reference to the service plane. The service plane illustrates that IN-supported services can be described to the end user or subscriber by means of a set of generic building blocks called "service features". This Recommendation describes this process of supporting services in an IN-structured network and the service plane’s relationship to the other planes in the IN Conceptual Model.