The present document provides the Stage One description of Location Services (LCS) on Global System for Mobile communications (GSM) networks. A Stage One description provides an overall service description@ primarily from the service subscriber's and user's points of view@ but not dealing with the details of the Man Machine Interface (MMI). This GTS includes information applicable to network operators@ service providers and terminal@ base station system@ switch and data base manufacturers. NOTE: Location Services may be considered as a network provided enabling technology consisting of standardized service capabilities which enables the provision of location applications. This application may be service provider specific. The description of the numerous and varied possible location applications which are enabled by this technology are outside the scope of this specification. However@ clarifying examples of how the functionality being specified may be used to provide specific location services is included in various sections of the specification. The present document contains the core requirements for the LCS on GSM to an extent sufficient to derive a complete definition of the LCS at the service level. However@ the present document also documents some additional requirements which may suggest in a non-normative manner certain ways the system may be implemented to support the LCS feature. LCS can be offered without subscription to basic telecommunication services. LCS is available to the following categories of LCS clients: Value Added Services LCS Clients - use LCS to support various value added services. These clients can include GSM MS subscribers as well as non-subscribers to other GSM services. PLMN Operator LCS Clients - use LCS to enhance or support certain OM related tasks@ supplementary services@ IN related services and GSM bearer services and teleservices. Emergency Services LCS Clients - use LCS to enhance support for emergency calls from GSM subscribers. Lawful Intercept LCS Clients - use LCS to support various legally required or sanctioned services. LCS is applicable to any target MS whether or not the MS supports LCS@ but with restrictions on choice of positioning method or notification of a location request to the MS user when LCS or individual positioning methods@ respectively@ are not supported by the MS. NOTE: It is envisioned that the specification of Location Services will be accomplished in a series of phased releases. These phases are described in GSM 10.71 [2] LCS will be developed in phases. Phase 1 includes provision of the following: LCS Phase 1. This is the initial default phase of LCS. It provides a generic flexible architecture capable of supporting all positioning methods. Specific support is provided for Time Of Arrival (TOA)@ Enhanced Observed Time Difference (E-OTD) and Global Positioning System (GPS) based positioning methods. Support is provided for emergency services@ value added services and PLMN operator services.