Section: Annex E (informative): Guidelines for enhancements to MS network capability IE and UE network capability IE
Content: The UE uses the information elements MS network capability and UE network capability to inform the core network about its network related capabilities. Both information elements can be signalled in any of the modes: A/Gb mode, Iu mode and S1 mode. The purpose of the present annex is to give some guidelines how to select the information element(s) to be enhanced if new capabilities need to be added. 1) If a capability is related to a feature that can be used in a network supporting A/Gb mode only or Iu mode only or both, the capability will be signalled in the MS network capability IE. 2) If a capability is related to a feature that can be used in network supporting S1 mode only, the capability will be signalled in the UE network capability IE. 3) If a capability is related to a feature that can be used only in a network supporting both S1 mode and at least one of the two modes A/Gb mode and Iu mode, the capability is added only to one of the two information elements: a) If the information is used by the MME only, the capability will be signalled in the UE network capability IE. b) If the information is used by the SGSN only or both by the SGSN and by the MME, the capability will be signalled in the MS network capability IE. NOTE: The reason for rules 1 and 2 is that a UE not supporting A/Gb mode and Iu mode will not provide the MS network capability IE to the network and a UE not supporting S1 mode will not provide the UE network capability IE. In some cases, due to rules 1 and 2 the capability indicator will be included in both information elements. EXAMPLE 1: The support indicator for UCS2 is included in both information elements. EXAMPLE 2: The "SRVCC to GERAN/UTRAN capability" is included in the MS network capability IE, as it is used both by the MME for SRVCC from E-UTRAN to GERAN/UTRAN and by the SGSN for SRVCC from UTRAN HSPA to GERAN/UTRAN.