Section: 6.1.3.13 Handling of network rejection not due to based congestion control
Content: The network may include a back-off timer value in a session management reject message to regulate the time interval at which the MS may retry the same procedure. For SM cause values other than #26 "insufficient resources", the network may also include the re-attempt indicator to indicate whether the MS is allowed to re-attempt the corresponding EPS session management procedure for the same in S1 mode after inter-system change. NOTE 1: If the network includes this back-off timer value, then the MS is blocked from sending another SM request for the same procedure for the same PLMN and combination for the specified duration. Therefore, the operator needs to exercise caution in determining the use of this timer value. NOTE 2: If the re-attempt indicator is not provided by the network, an MS registered in its HPLMN or in an EHPLMN (if the EHPLMN list is present) can use the configured SM_RetryAtRATChange value specified in the NAS configuration MO or in the USIM NASCONFIG file to derive the re-attempt indicator as specified in subclauses 6.1.3.1.3.3, 6.1.3.2.2.3, and 6.1.3.3.3.3. If re-attempt in S1 mode is allowed, the MS shall consider the back-off timer to be applicable only to the GPRS session management in A/Gb and Iu mode for the rejected session management procedure and the given PLMN and combination. If re-attempt in S1 mode is not allowed, the MS shall consider the back-off timer to be applicable to both NAS protocols, i.e. applicable to the GPRS session management in A/Gb and Iu mode for the rejected session management procedure and to the EPS session management in S1 mode for the corresponding EPS session management procedure and the given PLMN and combination. The APN of the PLMN and APN combination associated with the back-off timer is the APN sent by the MS when the PDN connection is established. If no APN is included in the ACTIVATE PDP CONTEXT REQUEST message, then the back-off timer is associated with the combination of the PLMN and no APN. For this purpose the MS shall memorize the APN provided to the network during the PDP context activation. The back-off timer associated with the combination of a PLMN with no APN will never be started due to any SM procedure related to an emergency PDN connection. If the back-off timer associated with the combination of a PLMN with no APN is running, it does not affect the ability of the MS to request an emergency PDN connection. The network may additionally indicate in the re-attempt indicator that a command to back-off is applicable not only for the PLMN in which the MS received the session management reject message, but for each PLMN included in the equivalent PLMN list at the time when the session management reject message was received. If the back-off timer is running or is deactivated for a given PLMN and APN combination, and the MS is an MS configured to use AC11 – 15 in selected PLMN, then the MS is allowed to initiate any GPRS session management procedure for this PLMN and APN combination.