The present document is the first part of the 3GPP Specification defining the Application Programming Interface (API) for Open Service Access (OSA), and provides an overview of the content and structure of the various parts of this specification, and of the relation to other standards documents.

The OSA-specifications define an architecture that enables service application developers to make use of network functionality through an open standardised interface, i.e. the OSA APIs. The concepts and the functional architecture for the OSA are contained in 3GPP TS 23.198 [3]. The requirements for OSA are contained in 3GPP TS 22.127 [2].

This specification has been defined jointly between 3GPP TSG CT WG5, ETSI TISPAN and The Parlay Group, in cooperation with a number of JAIN™ Community member companies.

Maintenance of up to 3GPP Rel-8 and new OSA Stage 1, 2 and 3 work beyond Rel-9 was moved to OMA in June 2008.