Section: 4.7.3 GPRS attach procedure
Content: The GPRS attach procedure is used for the following purposes: - normal GPRS attach, performed by the MS to IMSI attach for GPRS services only. The normal GPRS attach procedure shall be used: - by GPRS MSs in MS operation mode C, independent of the network operation mode; - by GPRS MSs in MS operation modes A or B if the network operates in network operation mode II; and - by GPRS MSs in MS operation mode A, independent of the network operation mode, if a circuit-switched transaction is ongoing; - combined GPRS attach procedure, used by GPRS MSs in MS operation modes A or B to attach the IMSI for GPRS and non-GPRS services provided that the network operates in network operation mode I. - GPRS attach for emergency bearer services, performed by the MS to IMSI or IMEI attach to emergency bearer services. The lower layers indicate to NAS that the network does not support emergency bearer services for the MS in limited service state (see 3GPP TS 25.331[ None ]  [23c]). This information is taken into account when deciding whether to initiate attach for emergency bearer services. With a successful GPRS attach procedure a GMM context is established. When the timer T3346 is running, MS is allowed to initiate an attach procedure if: - the MS is an MS configured to use AC11 – 15 in selected PLMN; - the MS is attaching for emergency bearer services; or - the MS has timer T3346 running because a request from an MS with the low priority indicator set to "MS is configured for NAS signalling low priority" was rejected, and the MS needs to attach without the low priority indicator, or with the low priority indicator set to "MS is not configured for NAS signalling low priority". An eCall only mobile station that is not capable of eCall over IMS shall not perform a normal or combined GPRS attach procedure. An eCall only mobile station that is capable of eCall over IMS may perform a normal or combined GPRS attach procedure only upon failure of a routing area updating procedure following intersystem change from S1 mode to A/Gb or Iu mode. When the MS moves from NG-RAN coverage to GERAN coverage, or from NG-RAN coverage to UTRAN coverage, the MS shall perform a normal or combined GPRS attach procedure, if the following applies: - the MS initiated a registration procedure while in N1 mode; and - since then the MS did not perform a successful EPS attach or tracking area updating procedure in S1 mode or GPRS attach or routing area updating procedure in A/Gb mode or Iu mode. Subclause 4.7.3.1 describes the GPRS attach procedure to attach the IMSI only for GPRS services. The combined GPRS attach procedure used to attach the IMSI for both GPRS and non-GPRS services is described in subclause 4.7.3.2. GPRS attach for emergency bearer services is described as part of subclause 4.7.3.1. If an IMSI attach for non-GPRS services is requested and a GMM context exists, the routing area updating procedure shall be used as described in subclause 4.7.5.2. To limit the number of consecutive rejected attach attempts, a GPRS attach attempt counter is introduced. The GPRS attach attempt counter shall be incremented as specified in subclause 4.7.3.1.5. Depending on the value of the GPRS attach attempt counter, specific actions shall be performed. The GPRS attach attempt counter shall be reset when: - the MS is powered on; - a SIM/USIM is inserted; - a GPRS attach or combined GPRS attach procedure is successfully completed; - an attach or combined attach procedure is successfully completed in S1 mode; - a combined GPRS attach procedure is completed for GPRS services only with cause #2, #16, #17, #22 or #28; - a GPRS attach or combined GPRS attach procedure is rejected with cause #11, #12, #13, #14 ,#15 or #25; - a network initiated detach procedure is completed with cause #11, #12, #13, #14, #15 or #25; or - a new PLMN is selected; and additionally when the MS is in substate ATTEMPTING-TO-ATTACH: - expiry of timer T3302; - a new routing area is entered; - an attach is triggered by CM sublayer requests; - timer T3346 is started. The mobile equipment shall contain a list of "forbidden location areas for roaming", as well as a list of "forbidden location areas for regional provision of service". The handling of these lists is described in subclause 4.4.1; the same lists are used by GMM and MM procedures. In a shared network, the MS shall choose one of the PLMN identities as specified in 3GPP TS 23.122[ Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode ]  [14]. The MS shall construct the Routing Area Identification of the cell from this chosen PLMN identity, and the LAC and the RAC received on the BCCH. For: - a shared GERAN, in A/Gb mode, the chosen PLMN identity is indicated to the GERAN in the first RLC data block of an upper layer PDU (see 3GPP TS 44.060[ None ]  [76]) when a foreign TLLI or a random TLLI is used by the network sharing supporting MS for the transmission. - a shared UTRAN, the chosen PLMN identity shall be indicated to the UTRAN in the RRC INITIAL DIRECT TRANSFER message (see 3GPP TS 25.331[ None ]  [23c]). For GERAN Iu mode, network sharing is not supported. Whenever an ATTACH REJECT message with the cause "PLMN not allowed" is received by the MS, the chosen PLMN indentity shall be stored in the "forbidden PLMN list" and if the MS is configured to use timer T3245 (see 3GPP TS 24.368[ Non-Access Stratum (NAS) configuration Management Object (MO) ]  [135] or 3GPP TS 31.102[ Characteristics of the Universal Subscriber Identity Module (USIM) application ]  [112]) then the MS shall start timer T3245 and proceed as described in subclause 4.1.1.6. Whenever an ATTACH REJECT message is received by the MS with the cause "Roaming not allowed in this location area", "Location Area not allowed", or "No suitable cells in Location Area", the LAI that is part of the constructed RAI shall be stored in the suitable list. The network informs the MS about the support of specific features, such as LCS-MOLR, MBMS, IMS voice over PS session, emergency bearer services in Iu mode in the Network feature supporti nformation element. The information is either explicitly given by sending the Network feature support IE or implicitly by not sending it. The handling in the network is described in subclause 9.4.2.9. The network can also use the Additional network feature support IE in order to inform the MS about the support of specific features such as the delivery of SMS via GPRS (GPRS-SMS) or implicitly by not sending it. The MS may use the support indications for LCS-MOLR, MBMS and GPRS-SMS to inform the user about the availability of the appropriate services. The MS shall not request the LCS-MOLR or MBMS services, if the service has not been indicated as available. The indication for MBMS is defined in subclause "MBMS feature support indication" in 3GPP TS 23.246[ Multimedia Broadcast/Multicast Service (MBMS); Architecture and functional description ]  [106]. In an MS with IMS voice over PS capability, the IMS voice over PS session indicator and the emergency bearer services indicator shall be provided to the upper layers. The upper layers take the IMS voice over PS session indicator into account as specified in 3GPP TS 23.221[ Architectural requirements ]  [131], subclause 7.2a and subclause 7.2b, when selecting the access domain for voice sessions or calls in Iu mode. When initiating an emergency call in Iu mode, the upper layers also take the emergency bearer services indicator into account for the access domain selection. The MS may use the GPRS-SMS indication in order to obtain SMS.