The 3rd Generation Partnership Project (3GPP) is the primary body for developing technology specifications for cellular networks. It self-organises through its Working Groups coordinated by the Chairs of the Technical Specifications Groups (TSGs). 

TSG SA (Service and System Aspects) has 6 active WGs.

The scope of SA1 - Services is on feature requirements applicable to mobile and fixed communications technology from 2G.

Outputs of this WG are Technical Specifications and Reports or changes to them. These are all submitted to TSG SA Approval. Once approved, they form the basis for work for the whole of 3GPP and industry segments interested in deploying networks based on IMS.