Section: 6.1.3.1.5 Abnormal cases
Content: The following abnormal cases can be identified: a) Expiry of timers In the mobile station: On the first expiry of the timer T3380, the MS shall resend the ACTIVATE PDP CONTEXT REQUEST and shall reset and restart timer T3380. This retransmission is repeated four times, i.e. on the fifth expiry of timer T3380, the MS shall release all resources possibly allocated for this invocation and shall abort the procedure; no automatic PDP context activation re-attempt shall be performed; and - if the ACTIVATE PDP CONTEXT REQUEST message was sent with request type set to "emergency", then the MS may inform the upper layers of the failure to establish the emergency bearer. NOTE: This can result in the upper layers requesting establishment of a CS emergency call (if not already attempted in the CS domain) or initiating other implementation specific mechanisms, e.g. procedures specified in 3GPP TS 24.229[ IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3 ]  [95] can result in the emergency call being attempted to another IP-CAN. On the network side: On the first expiry of the timer T3385, the network shall resend the message REQUEST PDP CONTEXT ACTIVATION and shall reset and restart timer T3385. This retransmission is repeated four times, i.e. on the fifth expiry of timer T3385, the network shall release possibly allocated resources for this activation and shall abort the procedure. b) Collision of MS initiated and network requested PDP context activation If the MS uses dynamic PDP addressing that turns out to collide with the network requested PDP address, then there is no detection of collision specified but left for network implementation. c) MS initiated PDP context activation request for an already activated PDP context (on the network side) i) If the network receives a ACTIVATE PDP CONTEXT REQUEST message with the same combination of APN, PDP type and PDP address as an already activated PDP context, the network shall deactivate the existing PDP context and, if any, all the linked PDP contexts (matching the combination of APN, PDP type and PDP address), locally without notification to the MS and proceed with the requested PDP context activation. ii) Alternatively (different combination of APN, PDP type and PDP address), if the NSAPI matches that of an already activated PDP context, then the network shall deactivate only the existing PDP context locally without notification to the MS and proceed with the requested PDP context activation. It is an implementation option if the parameters used for comparison described in clause i) and ii) are the parameters provided in the (current and previous) ACTIVATE PDP CONTEXT REQUESTs or the parameters which are the result of the application of the selection rules defined in 3GPP TS 23.060[ General Packet Radio Service (GPRS); Service description; Stage 2 ]  [74] Annex A.2. The parameter provided in the current ACTIVATE PDP CONTEXT REQUEST can not be compared to the actually used parameters (result of application of selection rules defined in 3GPP TS 23.060[ General Packet Radio Service (GPRS); Service description; Stage 2 ]  [74] Annex A.2) of the previously activated PDP contexts. If the network receives an ACTIVATE PDP CONTEXT REQUEST message with request type "emergency" and there already is a PDN connection for emergency bearer services existing, the network shall reject the request with cause code #31 "activation rejected, unspecified". d) Network initiated PDP context activation request for an already activated PDP context (on the mobile station side) If the MS receives a REQUEST PDP CONTEXT ACTIVATION message with the same combination of APN, PDP type and PDP address as an already activated PDP context, the MS shall deactivate the existing PDP context and, if any, all the linked PDP contexts (matching the combination of APN, PDP type and PDP address) locally without notification to the network and proceed with the requested PDP context activation. e) Additional MS initiated PDP context activation request received from an MS that is attached for emergency bearer services: If the MS is attached for emergency bearer services the network shall only accept the PDP context activation request for emergency services. The network shall reject any other PDP context activation request with cause code #31 "activation rejected, unspecified". f) Reception of the ACTIVATE PDP CONTEXT ACCEPT message and Bearer Control Mode violation If the Selected Bearer Control Mode indicates other value than 'MS only' in the ACTIVATE PDP CONTEXT ACCEPT message although the protocol configuration options information element was not present or the MS Support of Network Requested Bearer Control indicator was not present in the protocol configuration options information element of the corresponding ACTIVATE PDP CONTEXT REQUEST message, the MS shall ignore the Selected Bearer Control Mode parameter received from the network and apply Bearer Control Mode 'MS only' for all active PDP contexts sharing the same PDP Address and APN. Figure 6.3/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ] : MS initiated PDP context activation procedure Figure 6.4/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ] : Network initiated PDP context activation procedure