Section: 4.7.4.1.4 Abnormal cases in the MS
Content: The following abnormal cases can be identified: a) T3321 time-out On the first expiry of the timer, the MS shall retransmit the DETACH REQUEST message and shall reset and restart timer T3321. This retransmission is repeated four times, i.e. on the fifth expiry of timer T3321, the GPRS detach procedure shall be aborted, the MS shall change to state: - MM-NULL if "IMSI detach" was requested; - GMM-REGISTERED.NORMAL-SERVICE if "IMSI Detach" was requested; - GMM-DEREGISTERED if "GPRS detach" was requested; - GMM-DEREGISTERED and MM-NULL if "GPRS/IMSI" detach was requested. b) Lower layer failure before reception of DETACH ACCEPT message The detach procedure is aborted and the MS shall change to one of the following states, except in the following implementation option cases b.1, b.2 and b3: - MM-NULL if "IMSI detach" was requested; - GMM-REGISTERED.NORMAL-SERVICE if "IMSI Detach" was requested; - GMM-DEREGISTERED if "GPRS detach" was requested; - GMM-DEREGISTERED and MM-NULL if "IMSI/GPRS" detach was requested. b.1) Release of PS signalling connection before the completion of the GPRS detach procedure The release of the PS signalling connection before completion of the GPRS detach procedure shall result in the GPRS detach procedure being initiated again, if the following conditions apply: i) The original GPRS detach procedure was initiated over an existing PS signalling connection; and ii) No SECURITY MODE COMMAND message and no Non-Access Stratum (NAS) messages relating to the PS signalling connection (e.g. PS authentication procedure, see subclause 4.7.7) were received after the DETACH REQUEST message was transmitted. b.2) RR release in Iu mode (i.e. RRC connection release) with cause different than "Directed signalling connection re-establishment", for example, "Normal", or"User inactivity" (see 3GPP TS 25.331[ None ]  [23c] and 3GPP TS 44.118[ None ]  [111]) The GPRS detach procedure shall be initiated again, if the following conditions apply: i) The original GPRS detach procedure was initiated over an exisiting RRC connection; and ii) No SECURITY MODE COMMAND message and no Non-Access Stratum (NAS) messages relating to the PS signalling connection (e.g. PS authentication procedure, see subclause 4.7.7) were received after the DETACH REQUEST message was transmitted. NOTE: The RRC connection release cause different than "Directed signalling connection re-establishment" that triggers the re-initiation of the GPRS detach procedure is implementation specific. b.3) RR release in Iu mode (i.e. RRC connection release) with cause "Directed signalling connection re-establishment" (see 3GPP TS 25.331[ None ]  [23c] and 3GPP TS 44.118[ None ]  [111]) The routing area updating procedure shall be initiated followed by completion of the GPRS detach procedure if the following conditions apply: i) The original GPRS detach procedure was not due to SIM removal; and ii) The original GPRS detach procedure was not due to a rerun of the procedure due to "Directed signalling connection reestablishment". c) Detach procedure collision GPRS detach containing cause "power off": - If the MS receives a DETACH REQUEST message before the MS initiated GPRS detach procedure has been completed, this message shall be ignored and the MS initiated GPRS detach procedure shall continue. GPRS detach containing other causes than "power off": - If the MS receives a DETACH REQUEST message before the MS initiated GPRS detach procedure has been completed, the MS shall treat the message as specified in subclause 4.7.4.2.2 with the following modifications: - If the DETACH REQUEST message received by the MS contains detach type "re-attach required", and the MS initiated detach procedure is with detach type "GPRS detach" or "Combined GPRS/IMSI detach", the MS need not initiate the GPRS attach or combined GPRS attach procedure. - If the DETACH REQUEST message received by the MS contains detach type "IMSI detach", and the MS initiated detach procedure is with detach type "IMSI detach", the MS in operation mode A or B in network operation mode I need not re-attach to non-GPRS services. - If the DETACH REQUEST message received by the MS contains detach type "IMSI detach", and the MS initiated detach procedure is with detach type "GPRS detach" or "combined GPRS/IMSI detach", the MS shall progress both procedures. The MS in operation mode A or B in network operation mode I need not re-attach to non-GPRS services. d) Detach and GMM common procedure collision GPRS detach containing cause "power off": - If the MS receives a message used in a GMM common procedure before the GPRS detach procedure has been completed, this message shall be ignored and the GPRS detach procedure shall continue. GPRS detach containing other causes than "power off" and containing detach type "IMSI detach": - If the MS receives a message used in a GMM common procedure before the GPRS detach procedure has been completed, both the GMM common procedure and the GPRS detach procedure shall continue. GPRS detach containing other causes than "power off" and containing other detach types than "IMSI detach": - If the MS receives a P-TMSI REALLOCATION COMMAND, a GMM STATUS, or a GMM INFORMATION message before the GPRS detach procedure has been completed, this message shall be ignored and the GPRS detach procedure shall continue. - If the MS receives an AUTHENTICATION AND CIPHERING REQUEST or IDENTITY REQUEST message, before the GPRS detach procedure has been completed, the MS shall respond to it as described in subclauses 4.7.7 and 4.7.8 respectively. e) Change of cell within the same RA (A/Gb mode only) If a cell change occurs within the same RA before a DETACH ACCEPT message has been received, then the cell update procedure shall be performed before completion of the detach procedure. f) Change of cell into a new routing area If a cell change into a new routing area occurs before a DETACH ACCEPT message has been received, the GPRS detach procedure shall be aborted and re-initiated after successfully performing a routing area updating procedure. If the detach procedure is performed due to the removal of the SIM/USIM or the MS is to be switched off, the MS shall abort the detach procedure and enter the state GMM-DEREGISTERED. g) Access barred because of access class control or EAB The signalling procedure for GPRS detach shall not be started. The MS starts the signalling procedure as soon as possible and if still necessary, i.e. when the barred state is removed or because of a cell change, or performs a local detach immediately or after an implementation dependent time. h) Detach and paging for non-GRPS services procedure collision If the MS receives a paging for non-GPRS services before the MS initiated combined GPRS detach procedure with detach type "IMSI detach" or "GPRS/IMSI detach" has been completed, then the paging for non-GPRS services shall be ignored and the MS initiated combined GPRS detach procedure shall continue. Figure 4.7.4/1 3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ] : MS initiated GPRS detach procedure For the cases b and f: - Timer T3321 shall be stopped if still running.