Content for  TS 23.012  Word version:  18.0.0

Sheet 1: Decision "National Roaming Restrictions Exist?" distinguishes whether or not the subscriber is allowed service in the target LA, based on the current location of the MS and the VLR's knowledge of other networks. The "Yes" branch results in the sending of "Update Location Area Negative Response" toward the MSC (and the MS), with cause "National Roaming Not Allowed." However, subscriber data shall not be deleted from the VLR. This is to avoid unnecessary HLR updating should the subscriber be allowed subsequently to roam in other LAs of the same MSC. Sheet 1: Decision "Access-Restriction-Data permits current RAT?" performs a check on the subscriber's AccessRestrictionData information received from the HLR and either allows the operation to continue or rejects the Location Update. The decision is taken according to the following:

• If AccessRestrictionData value includes "GERAN not allowed" and the LA/RA, where the MS accesses the network, is served by GERAN, then the subscriber's access is not permitted.
• If AccessRestrictionData value includes "UTRAN not allowed" and the LA/RA, where the MS accesses the network is served by UTRAN, then the subscriber's access is not permitted.

Sheet 1: When the Location Update is not allowed because the subscriber access is restricted due to Administrative Restriction of Subscribers' Access feature, the flow results in the sending of "Update Location Area Negative Response" toward the MSC (and the MS). The recommended cause code is "RAT not allowed", but cause codes "PLMN not allowed" or "National Roaming Not allowed" may also be used based on operator configuration and the required MS behaviour. For the MS behaviour determined on the received cause code see TS 24.008. Sheet 1: Decision "Roaming restriction due to Unsupported Feature received in subscriber data?" distinguishes whether or not the subscriber data received from the HLR indicates "roaming restriction due to unsupported feature." The "Yes" branch results in the sending of "Update Location Area Negative Response" toward the MSC (and the MS), with cause "National Roaming Not Allowed." However, subscriber data shall not be deleted from the VLR. This is to avoid unnecessary HLR updating should the subscriber be allowed subsequently to roam in other LAs of the same MSC. Sheet 1: Decision "Regional subscription restriction" distinguishes whether or not the subscriber is allowed service in the target LA, which the VLR deduces based on regional subscription information received from the HLR. The "Yes" branch results in the sending of "Update Location Area Negative Response" toward the MSC (and the MS), with cause "location area not allowed." However, subscriber data shall not be deleted from the VLR. This is to avoid unnecessary HLR updating should the subscriber be allowed subsequently to roam in other LAs of the same MSC. Sheet 1: Causes "National Roaming Not Allowed" and "RAT not allowed" lead to sending of cause #13 (roaming not allowed in the Location Area) and #15 (no suitable cells in Location Area) respectively to the MS (see TS 29.010). On receipt of cause #13 or #15 the TMSI and LAI currently stored in the MS are not deleted (see TS 24.008). As an option (referred-to as "TMSI option"), for these two reject causes, the VLR may forward a new TMSI (with the new LAI) together with the sending of "Update Location Area Negative Response" toward the MSC. The Location Updating Reject is sent to the MS after forwarding of the new TMSI (and new LAI) (see clause 4.1.1.1). This optional TMSI allocation (with new LAI) ensures that:

• a pre-Rel-8 MS will initiate a location updating if it roams back to the previous Location Area (allowed), i.e. to the location area whose identity is already stored in the MS, after having received the reject cause #13 or #15; otherwise the location updating may not be initiated and mobile terminated calls may not be delivered until the next mobile originated activity or periodic location update (see TR 29.994).
• the next location update enables the new VLR to address the correct previous VLR (which controls the not allowed Location Area) and to obtain the right IMSI and security context; otherwise a wrong VLR is addressed (corresponding to the TMSI/LAI of the VLR that controlled the previous allowed LA) and a wrong IMSI / security context would be obtained if the TMSI was reallocated.

Sheet 2: If the MS performs a location update procedure in a VPLMN supporting Autonomous CSG Roaming and the HPLMN has enabled Autonomous CSG Roaming in the VPLMN (via Service Level Agreement) and if the VLR needs to retrieve the CSG Subscription Data of the MS from the CSS, the VLR shall initiate the Update VCSG Location Procedure with the CSS and store the CSG Subscription data if any received from the CSS. The stored CSG Subscription data is used by VLR to perform access control for the MS. If the Update VCSG Location Procedure fails, the VLR continues the location update procedure. Sheet 3: The procedure Check_IMEI_VLR is specified in TS 23.018.