Section: 4.5.1.1 MM connection establishment initiated by the mobile station
Content: Upon request of a CM entity to establish an MM connection the MM sublayer first decides whether to accept, delay, or reject this request: - An MM connection establishment may only be initiated by the mobile station when the following conditions are fulfilled: - Its update status is UPDATED. - The MM sublayer is in one of the states MM IDLE, RR CONNECTION RELEASE NOT ALLOWED or MM connection active but not in MM connection active (Group call). An exception from this general rule exists for emergency calls (see subclause 4.5.1.5). A further exception is defined in the following clause. - If an MM specific procedure is running at the time the request from the CM sublayer is received, and the LOCATION UPDATING REQUEST message has been sent, the request will either be rejected or delayed, depending on implementation, until the MM specific procedure is finished and, provided that the network has not sent a "follow-on proceed" indication, the RR connection is released. If the LOCATION UPDATING REQUEST message has not been sent, the mobile station may include a "follow-on request" indicator in the message. The mobile station shall then delay the request until the MM specific procedure is completed, when it may be given the opportunity by the network to use the RR connection: see subclause 4.4.4.6. In order to establish an MM connection, the mobile station proceeds as follows: a) If no RR connection exists, the MM sublayer requests the RR sublayer to establish an RR connection and enters MM sublayer state WAIT FOR RR CONNECTION (MM CONNECTION). This request contains an establishment cause and a CM SERVICE REQUEST message. When the establishment of an RR connection is indicated by the RR sublayer, the MM sublayer of the mobile station starts timer T3230, gives an indication to the CM entity that requested the MM connection establishment, and enters MM sublayer state WAIT FOR OUTGOING MM CONNECTION. b) If an RR connection is available, the MM sublayer of the mobile station sends a CM SERVICE REQUEST message to the network, starts timer T3230, stops and resets timer T3241, gives an indication to the CM entity that requested the MM connection establishment, and enters: - MM sublayer state WAIT FOR OUTGOING MM CONNECTION, if no MM connection is active; - MM sublayer state WAIT FOR ADDITIONAL OUTGOING MM CONNECTION, if at least one MM connection is active; - If an RR connection exists but the mobile station is in the state WAIT FOR NETWORK COMMAND then any requests from the CM layer that are received will either be rejected or delayed until this state is left. c) Only applicable for mobile stations supporting VGCS talking: If a mobile station which is in the MM sublayer state MM IDLE, service state RECEIVING GROUP CALL (NORMAL SERVICE), receives a request from the GCC sublayer to perform an uplink access, the MM sublayer requests the RR sublayer to perform an uplink access procedure and enters MM sublayer state WAIT FOR RR CONNECTION (GROUP TRANSMIT MODE). When a successful uplink access is indicated by the RR sublayer, the MM sublayer of the mobile station gives an indication to the GCC sublayer and enters MM sublayer state MM CONNECTION ACTIVE (GROUP TRANSMIT MODE). When an uplink access reject is indicated by the RR sublayer, the MM sublayer of the mobile station gives an indication to the GCC sublayer and enters the MM sublayer state MM IDLE, service state RECEIVING GROUP CALL (NORMAL SERVICE). In the network, if an uplink access procedure is performed, the RR sublayer in the network provides an indication to the MM sublayer together with the mobile subscriber identity received in the TALKER INDICATION message. The network shall then enter the MM sublayer state MM CONNECTION ACTIVE (GROUP TRANSMIT MODE). d) When the MS is IMSI attached for CS services via EMM combined procedures, as described in 3GPP TS 24.301[ Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 ]  [120], and the MS is camping on an E-UTRAN cell, and if T3246 is not running, the MM sublayer requests EMM to initiate a service request procedure for CS fallback. The MM connection establishment is delayed until the MS changes to a GERAN or UTRAN cell. If the MS enters a GERAN or UTRAN cell, then the MS shall initiate the MM connection establishment and send a CM SERVICE REQUEST message. The MS shall include the Additional update parameters information element indicating "CS fallback mobile originating call". If the MS determines that it is in a different location area than the stored location area, the MS shall first initiate a normal location updating procedure regardless of Network Mode of Operation. If the location area of the current cell is not available, the MS may initiate a normal location updating procedure directly. The MM connection establishment is delayed until successful completion of the normal location updating procedure. Additionally the MS performs routing area updating as specified in subclause 4.7.5. If the normal location updating procedure is initiated, the MS shall indicate the "follow-on request pending", shall include the Additional update parameters information element indicating"CS fallback mobile originating call", and shall not include the MS network feature support information element in the LOCATION UPDATING REQUEST message. In case a, b and d, the CM SERVICE REQUEST message contains the: - mobile identity according to subclause 10.5.1.4; - mobile station classmark 2; - ciphering key sequence number; and - CM service type identifying the requested type of transaction (e.g. mobile originating call establishment, emergency call establishment, short message service, supplementary service activation, location services). A MS supporting eMLPP may optionally include a priority level in the CM SERVICE REQUEST message. For MM connection establishment involving a shared GERAN network in A/Gb mode, if the MS is a GERAN network sharing supporting MS, the chosen PLMN identity shall be indicated to the GERAN in the CM SERVICE REQUEST message using the Skip Indicator IE as specified in subclause 10.3.1. A collision may occur when a CM layer message is received by the mobile station in MM sublayer state WAIT FOR OUTGOING MM CONNECTION or in WAIT FOR ADDITIONAL OUTGOING MM CONNECTION. In this case the MM sublayer in the MS shall establish a new MM connection for the incoming CM message as specified in subclause 4.5.1.3. Upon receiving a CM SERVICE REQUEST message, the network shall analyse its content. The type of semantic analysis may depend on other on going MM connection(s). Depending on the type of request and the current status of the RR connection, the network may start any of the MM common procedures and RR procedures. In A/Gb mode, the network may initiate the classmark interrogation procedure, for example, to obtain further information on the mobile station's encryption capabilities. The identification procedure (see subclause 4.3.3) may be invoked for instance if a TMSI provided by the mobile station is not recognized. The network may invoke the authentication procedure (see subclause 4.3.2) depending on the CM service type. In A/Gb mode, the network decides also if the ciphering mode setting procedure shall be invoked (see subclause 3.4.7 in 3GPP TS 44.018[ None ]  [84]). In Iu mode, the network decides also if the security mode control procedure shall be invoked (see 3GPP TS 25.331[ None ]  [23c] and 3GPP TS 44.118[ None ]  [111]). NOTE 1: If the CM_SERVICE_REQUEST message contains a priority level the network may use this to perform queuing and pre-emption as defined in 3GPP TS 23.067[ enhanced Multi-Level Precedence and Pre-emption Service (eMLPP); Stage 2 ]  [88]. In A/Gb mode, the MS shall consider the MM connection establishment to be completed when: - receiving an indication from the RR sublayer that the ciphering mode setting procedure is completed; or - receiving a CM SERVICE ACCEPT message. In Iu mode, the MS shall consider the MM connection establishment to be completed when - receiving an indication from the RR sublayer that the security mode control procedure is completed, except for the case when it is the first security mode control procedure after successful inter-system change received in MM sublayer state WAIT FOR ADDITIONAL OUTGOING MM CONNECTION; or - receiving a CM SERVICE ACCEPT message. The procedures in subclause 4.1.1.1.1 shall always have precedence over this subclause. In Iu mode, during a MM connection establishment for all services, except for emergency call (see subclause 4.1.1.1.1), the security mode control procedure with activation of integrity protection shall be invoked by the network unless integrity protection is already started (see subclause 4.1.1.1.1). The MM connection establishment is completed, timer T3230 shall be stopped, the CM entity that requested the MM connection shall be informed, and MM sublayer state MM CONNECTION ACTIVE is entered. The MM connection is considered to be active. If the service request cannot be accepted, the network returns a CM SERVICE REJECT message to the mobile station. The reject cause information element (see subclause 10.5.3.6 and annex G) indicates the reason for rejection. The following cause values may apply: #4: IMSI unknown in VLR #6: Illegal ME #17: Network failure #22: Congestion #25 Not authorized for this CSG #32: Service option not supported #33: Requested service option not subscribed #34: Service option temporarily out of order If the service request is rejected due to general NAS level mobility management congestion control, the network shall set the MM cause value to #22 "congestion" and assign a back-off timer T3246 (see 3GPP TS 23.012[ Location management procedures ]  [140]). If no other MM connection is active, the network may start the RR connection release (see subclause 3.5 of 3GPP TS 44.018[ None ]  [84] (A/Gb mode only), 3GPP TS 25.331[ None ]  [23c] (UTRAN Iu mode only), or in 3GPP TS 44.118[ None ]  [111] (GERAN Iu mode only) when the CM SERVICE REJECT message is sent. If a CM SERVICE REJECT message is received by the mobile station, timer T3230 shall be stopped, the requesting CM sublayer entity informed. Then the mobile station shall proceed as follows: - If the cause value is not #4 or #6 or #25 received from a CSG cell and the MS is in UTRAN Iu mode, the MM sublayer returns to the previous state (the state where the request was received). Other MM connections shall not be affected by the CM SERVICE REJECT message. - If cause value #4 is received, the mobile station aborts any MM connection, deletes any TMSI, LAI and ciphering key sequence number in the SIM/USIM, changes the update status to NOT UPDATED (and stores it in the SIM/USIM according to subclause 4.1.2.2), and enters the MM sublayer state WAIT FOR NETWORK COMMAND. If subsequently the RR connection is released or aborted, this will force the mobile station to initiate a normal location updating). Whether the CM request shall be memorized during the location updating procedure, is a choice of implementation. - If cause value #6 is received, the mobile station aborts any MM connection, deletes any TMSI, LAI and ciphering key sequence number in the SIM/USIM, changes the update status to ROAMING NOT ALLOWED (and stores it in the SIM/USIM according to subclause 4.1.2.2), and enters the MM sublayer state WAIT FOR NETWORK COMMAND. The mobile station shall consider the SIM/USIM as invalid for non-GPRS services until switch-off or the SIM/USIM is removed. If the message has been successfully integrity checked by the lower layers and the MS maintains a counter for "SIM/USIM considered invalid for non-GPRS services", then the MS shall set this counter to MS implementation-specific maximum value. - If cause value #22 is received, the T3246 value IE is present in the CM SERVICE REJECT message and the value indicates that this timer is neither zero nor deactivated, the MS shall check whether the CM SERVICE REJECT message with cause #22 is integrity protected and shall stop timer T3246 if it is running. If the message is integrity protected, the MS shall start timer T3246 with the value provided in the T3246 value IE. Otherwise, the MS shall start timer T3246 with a random value from the default range specified in table 11.1.The MS stays in the current serving cell and applies normal cell reselection process. The service request procedure may be started by CM layer, if it is still necessary, when timer T3246 expires or is stopped. If cause value #22 is received, the T3246 value IE is not present in the CM SERVICE REJECT message or if the T3246 value IE the value indicates that this timer is zero or deactivated, the same actions as on timer expiry in subclause 4.5.1.2 shall be taken by the mobile station. - If cause value #25 is received from a CSG cell and the MS is in UTRAN Iu mode, the MS shall check whether the CM SERVICE REJECT message with cause #25 is integrity protected. If the message is not integrity protected, the MS shall discard the message. Otherwise, the MS shall abort any MM connection, remove the entry corresponding to the CSG ID and associated PLMN identity of the cell where the MS has sent the CM SERVICE REQUEST message from the Allowed CSG list if the CSG ID and associated PLMN identity are contained in the Allowed CSG list, and enter the MM sublayer state WAIT FOR NETWORK COMMAND. If the CSG ID and associated PLMN identity of the cell where the MS has sent the CM SERVICE REQUEST message is contained in the Operator CSG list, the MS shall proceed as specified in 3GPP TS 23.122[ Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode ]  [14] subclause 3.1A. Subsequently, after the RR connection is released or aborted, the MS applies normal cell reselection process. If cause value #25 is received and the cell is not a CSG cell or the MS is not in UTRAN Iu mode, the MS shall discard the CM SERVICE REJECT message.