The PDP Context Deactivation Initiated by SGSN procedure is illustrated in Figure 76.
This procedure is also used as part of the SIPTO using GW selection function when the SGSN determines that GW relocation is desirable. In this situation the SGSN deactivates the relevant PDN connection(s) using the "reactivation requested" cause value, and the UE should then re-establish those PDN connection(s) towards the same APN(s).
If the PDP Context was served by a GGSN, the SGSN sends a Delete PDP Context Request (TEID, NSAPI, Teardown Ind, CGI/SAI) message to the GGSN. If Teardown Ind is included by the SGSN, the GGSN deactivates all PDP contexts associated with this PDP address and the same APN. The GGSN removes the PDP context and returns a Delete PDP Context Response (TEID) message to the SGSN. If the MS was using a dynamic PDP address allocated by the GGSN, and if the context being deactivated is the last PDP context associated with this PDP address, the GGSN releases this PDP address and makes it available for subsequent activation by other MSs. The Delete PDP Context messages are sent over the backbone network. The SGSN may not wait for the response from the GGSN before sending the Deactivate PDP Context Request message. For PDP Context using a T6b connection to the SCEF the SGSN indicates to the SCEF that the connection for the MS is no longer available according to TS 23.682
The GGSN may interact with PCRF (refer to TS 23.203
), e.g. to deliver User Location Information and/or UE Time Zone Information if it was requested by the PRCF.
The SGSN sends a Deactivate PDP Context Request (TI, Teardown Ind, Cause, WLAN offloadability indication) message to the MS. If Teardown Ind is included, all PDP contexts associated with this PDP address and the same APN are deactivated. The MS removes the PDP context(s) and returns a Deactivate PDP Context Accept (TI) message to the SGSN. If this deactivates the last PDP context of the UE then an E-UTRAN capable MS not using CIoT GSM Optimization shall set its TIN to "P-TMSI". If PDP contexts remain for the MS, the SGSN recalculates the UE-AMBR and updates the RAN accordingly.
If the request is deactivation with reactivation from SGSN, the UE starts MS initiated PDP context Activation Procedure as specified in clauses 126.96.36.199
and 188.8.131.52A by using the same APN of the released PDN connection.
The SGSN may include an indication whether the traffic of this PDP context is allowed to be offloaded to WLAN as described in clause 5.3.21
if some PDP contexts associated with this PDP address and the same APN are not deactivated.
In Iu mode, radio access bearer release is done by the RAB Assignment procedure.
In A/Gb mode, BSS packet flow context procedures may be executed. These procedures are defined in clause "BSS Context".
The SGSN determines the Maximum APN Restriction for the remaining PDP contexts and stores this new value for the Maximum APN Restriction.
The CAMEL procedure call shall be performed, see referenced procedure in TS 23.078
The procedure returns as result "Continue".