Section: 12.5 Service Area Identifier
Content: The Service Area Identifier (SAI) is used to identify an area consisting of one or more cells belonging to the same Location Area. Such an area is called a Service Area and can be used for indicating the location of a UE to the CN. The Service Area Code (SAC) together with the PLMN-Id and the LAC constitute the Service Area Identifier. - SAI = PLMN-Id || LAC || SAC The SAC is defined by the operator, and set in the RNC via O&M. For the syntax description and the use of this identifier in RANAP signalling, see 3GPP TS 25.413[ UTRAN Iu interface Radio Access Network Application Part (RANAP) signalling ]  [17]. 3GPP TS 25.423[ UTRAN Iur interface Radio Network Subsystem Application Part (RNSAP) signalling ]  [37] and 3GPP TS 25.419[ UTRAN Iu-BC interface: Service Area Broadcast Protocol (SABP) ]  [38] define the use of this identifier in RNSAP and SABP signalling. A cell may belong to one or two Service Areas. If it belongs to two Service Areas, one is applicable in the Broadcast (BC) domain and the other is applicable in both the CS and PS domains. The Broadcast (BC) domain requires that its Service Areas each consist of only one cell. This does not limit the use of Service Areas for other domains. Refer to 3GPP TS 25.410[ UTRAN Iu interface: General aspects and principles ]  [39] for a definition of the BC domain.