Section: 7.3.12 Detach Notification
Content: A Detach Notification message shall be sent from an MME to the associated SGSN, or from an SGSN to the associated MME as a part of Detach procedure if the ISR is activated between the MME and SGSN for the UE. Possible Cause values are: "Local Detach". "Complete Detach". A Detach Notification message shall also be sent from an SGSN to the associated MME as a part of Detach procedure if the ISR is activated between the MME and SGSN for the UE. Possible Cause values are: "IMSI Detach only". "Local Detach" indicates that this detach is local to the MME/SGSN and so the associated SGSN/MME registration where the ISR is activated shall not be detached. The MME/SGSN that receives this message including this Cause value of "Local Detach" only deactivates the ISR. This Cause value shall be included in the procedures: MME/SGSN-initiated Detach Procedure in case of implicit detach. "Complete Detach" indicates both the MME registration and the SGSN registration that the ISR is activated for, shall be detached. This "Complete Detach" Cause value shall be included in the procedures: UE-initiated Detach Procedure. MME/SGSN-initiated Detach Procedure in case of explicit detach. For the purpose of SGs handling, the SGSN shall include Detach Type in the Detach Notification message for "Complete Detach" when the UE is combined IMSI/EPS attached and the ISR is activated. Possible Detach Type values are: "PS Detach". "Combined PS/CS Detach". "PS Detach" indicates that the MME shall perform explicit IMSI detach from EPS service as specified in clause 5.4, 3GPP TS 29.118[ Mobility Management Entity (MME) - Visitor Location Register (VLR) SGs interface specification ]  [22]. "Combined PS/CS detach" indicates that the MME shall perform explicit IMSI detach from non-EPS service as specified in clause 5.5, 3GPP TS 29.118[ Mobility Management Entity (MME) - Visitor Location Register (VLR) SGs interface specification ]  [22]. "IMSI Detach only" indicates that combined IMSI/EPS attached UE initiates IMSI only GPRS detach from non-GPRS service as specified in clause 4.7.4.1, 3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ]  [5], and both the SGSN/MME registration shall be remained. The MME shall perform explicit IMSI detach from non-EPS service for the SGs handling purpose, which is specified in clause 5.5, 3GPP TS 29.118[ Mobility Management Entity (MME) - Visitor Location Register (VLR) SGs interface specification ]  [22]. This "IMSI Detach only" Cause value shall be included in the procedures: UE-initiated Detach Procedure for GERAN/UTRAN for "IMSI Detach only". Table -1 specifics the presence of the IEs in the message. Table -1: Information Elements in a Detach Notification