Section: 6.1.3.3 PDP context modification procedure
Content: The PDP context modification procedure is invoked by the network or by the MS, in order to: - inform about the change of the 3GPP PS data off UE status for a PDN connection; - change the QoS negotiated; - change the Radio priority level; or - change the TFT, negotiated during the PDP context activation procedure, the secondary PDP context activation procedure or at previously performed PDP context modification procedures. Depending on the selected Bearer Control Mode being 'MS only' or 'MS/NW', the MS or the network respectively may also create and delete a TFT of an active default PDP context. The PDP context modification procedure can be initiated by the network or the MS at any time when a PDP context is active. The network and the MS shall manage packet filter identifiers for the packet filters each modifies or deletes. The network and the MS shall manage packet filter evaluation precedence for the packet filters each modifies.If the MS changes a TFT, which is not assigned to a default PDP context, the MS shall ensure that at least one packet filter applicable for the uplink direction remains among the packet filters created by the MS in that TFT, or no own packet filters . If the network changes a TFT, which is not ass igned to a default PDP context, the network shall ensure that at least one packet filter applicable for the uplink direction remains among the TFT packet filters created by the network in that TFT, or no own packet filters. The MS supporting S1 mode shall not modify the QoS of the first PDP context that was established within the PDN connection. The MS not supporting S1 mode should not modify the QoS of the first PDP context that was established within the PDN connection (see 3GPP TS 23.060[ General Packet Radio Service (GPRS); Service description; Stage 2 ]  [74]). To indicate a change of 3GPP PS data off UE status for a PDN connection, the MS shall include the protocol configuration options IE in the MODIFY PDP CONTEXT REQUEST message and set the 3GPP PS data off UE status only if the network included the 3GPP PS data off support indication for the PDN connection established by the PDP context activation procedure. The MS behaves as described in subclause 4.7.1.10. When the PDP context modification procedure is used to indicate a change of 3GPP PS data off UE status for a PDN connection (see subclause 4.7.1.10), the UE shall initiate the PDP context modification procedure even if the timer T3396 or the back-off timer is running or is deactivated. The PDP context modification procedure may also be invoked by the MS, in order to upgrade the maximum bit rate and to trigger the re-establishment of the radio access bearer for an activated PDP context which is preserved in the MS with maximum bit rate values of 0kbit/s for both uplink and downlink (see 3GPP TS 23.060[ General Packet Radio Service (GPRS); Service description; Stage 2 ]  [74]). NOTE 1: As described in 3GPP TS 23.060[ General Packet Radio Service (GPRS); Service description; Stage 2 ]  [74], the MS only preserves PDP contexts with a TFT including packet filter(s) set by the MS. If - the PDP Context Modification request is accepted by the network but the radio access bearer is not established; or - the PDP Context Modification request is rejected with cause "insufficient resources" (see subclause 6.1.3.3.3), then the MS is not required to start a new PDP Context Modification procedure or to start a Service Request procedure in order to trigger the re-establishment of the radio access bearer. If there is a PDN connection for emergency bearer services established, the MS shall not request a modification of bearer resources for this PDN connection. The network requested PDP context modification procedure may also be used to update the PDP address when external PDP address allocation is performed, in which case the MS receives the PDP address in the MODIFY PDP CONTEXT REQUEST (Network to MS direction) message. NOTE 2: The procedure may be initiated by the network due to an inter-SGSN Routing Area Updating when a PDP context is active. The network requested PDP context modification procedure may also be used to update the WLAN offload indication, in which case the MS receives the updated WLAN offload indication in the MODIFY PDP CONTEXT REQUEST (Network to MS direction) message.