Section: 4.7.4.2.4 Abnormal cases on the network side
Content: The following abnormal cases can be identified: a) T3322 time-out On the first expiry of the timer, the network shall retransmit the DETACH REQUEST message and shall start timer T3322. This retransmission is repeated four times, i.e. on the fifth expiry of timer T3322, the GPRS detach procedure shall be aborted. If the detach type indicates "IMSI detach", or "re-attach not required" and the cause code is #2 "IMSI unknown in HLR", the network shall not change the current GMM state; otherwise the network shall change state to GMM-DEREGISTERED. b) Low layer failure The GPRS detach procedure is aborted. If the detach type indicates "IMSI detach", or "re-attach not required" and the cause code is #2 "IMSI unknown in HLR", the network shall not change the current GMM state; otherwise the network shall change state to GMM-DEREGISTERED. c) GPRS detach procedure collision If the network receives a DETACH REQUEST message with "switching off" indicated, before the network initiated GPRS detach procedure has been completed, both procedures shall be considered completed. If the network receives a DETACH REQUEST message without "switching off" indicated, before the network initiated GPRS detach procedure has been completed, the network shall send a DETACH ACCEPT message to the MS. d) GPRS detach and GPRS attach procedure collision If the network receives an ATTACH REQUEST message before the network initiated GPRS detach procedure with type of detach 're-attach not required' has been completed, the network shall ignore the ATTACH REQUEST message. If the detach type IE value, sent in the DETACH REQUEST message, indicates "re-attach required" the detach procedure is aborted and the GPRS attach procedure shall be progressed after the PDP contexts and MBMS contexts, if any, have been deleted. If the detach type IE value, sent in the DETACH REQUEST message, indicates "IMSI detach" the detach procedure is aborted and the GPRS attach procedure shall be progressed. e) GPRS detach and routing area updating procedure collision GPRS detach containing detach type "re-attach required" or "re-attach not required": If the network receives a ROUTING AREA UPDATE REQUEST message before the network initiated GPRS detach procedure has been completed, the detach procedure shall be progressed, i.e. the ROUTING AREA UPDATE REQUEST message shall be ignored. If the DETACH REQUEST message contains detach type "re-attach not required" and GMM cause #2 "IMSI unknown in HLR", the network will follow the procedure as described below for the detach type "IMSI detach". GPRS detach containing detach type "IMSI detach": If the network receives a ROUTING AREA UPDATE REQUEST message before the network initiated GPRS detach procedure has been completed, the network shall abort the detach procedure, shall stop T3322 and shall progress the routing area update procedure. f) GPRS detach and service request procedure collision GPRS detach containing detach type "re-attach required" or "re-attach not required": If the network receives a SERVICE REQUEST message before the network initiated GPRS detach procedure has been completed, the network shall progress the detach procedure. If the GPRS Detach Request message contains detach type "re-attach not required" and GMM cause #2 "IMSI unknown in HLR", the network will follow the procedure as described below for the detach type "IMSI detach". GPRS detach containing detach type "IMSI detach": If the network receives a SERVICE REQUEST message before the network initiated GPRS detach procedure has been completed, the network shall progress both procedures. Figure 4.7.4/2 3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ] : Network initiated GPRS detach procedure