4.7.2 GPRS Mobility management timers and UMTS PS signalling connection control

24.0083GPPCore network protocolsMobile radio interface Layer 3 specificationRelease 18Stage 3TS

4.7.2.1 READY timer behaviour

4.7.2.1.1 READY timer behaviour (A/Gb mode only)

The READY timer, T3314 is used in the MS and in the network per each assigned P-TMSI to control the cell updating procedure.

When the READY timer is running or has been deactivated the MS shall perform cell update each time a new cell is selected (see 3GPP TS 43.022 [82]). If a routing area border is crossed, a routing area updating procedure shall be performed instead of a cell update.

When the READY timer has expired:

– the MS shall perform the routing area updating procedure when a routing area border is crossed;

– the MS shall not perform a cell update when a new cell is selected.

– the network shall page the MS if down-link user data or signalling information needs to be sent to the MS.

All other GMM procedures are not affected by the READY timer.

The READY timer is started:

– in the MS when the GMM entity receives an indication from lower layers that an LLC frame other than LLC NULL frame has been transmitted on the radio interface; and

– in the network when the GMM entity receives an indication from lower layers that an LLC frame other than LLC NULL frame has been successfully received by the network.

Within GMM signalling procedures the network includes a "force to standby" information element, in order to indicate whether or not the READY timer shall be stopped when returning to the GMM-REGISTERED state. If the "force to standby" information element is received within more than one message during a ongoing GMM specific procedure, the last one received shall apply. If the READY timer is deactivated and the network indicates "force to standby" with the "force to standby" information element, this shall not cause a modification of the READY timer.

The READY timer is not affected by state transitions to and from the GMM-REGISTERED.SUSPENDED sub-state.

The value of the READY timer may be negotiated between the MS and the network using the GPRS attach or GPRS routing area updating procedure.

– If the MS wishes to indicate its preference for a READY timer value it shall include the preferred values into the ATTACH REQUEST and/or ROUTING AREA UPDATE REQUEST messages. The preferred values may be smaller, equal to or greater than the default values or may be equal to the value requesting the READY Timer function to be deactivated.

– Regardless of whether or not a timer value has been received by the network in the ATTACH REQUEST or ROUTING AREA UPDATE REQUEST messages, the network may include a timer value for the READY timer (different or not from the default value) into the ATTACH ACCEPT or ROUTING AREA UPDATE ACCEPT messages, respectively. If the READY Timer value was included, it shall be applied for the GMM context by the network and by the MS.

– When the MS proposes a READY Timer value and the Network does not include any READY Timer Value in its answer, then the value proposed by the MS shall be applied for the GMM context by the Network and by the MS.

– When neither the MS nor the Network proposes a READY Timer value into the ATTACH REQUEST/ATTACH ACCEPT or ROUTING AREA UPDATE REQUEST/ROUTING AREA UPDATE ACCEPT message, then the default value shall be used.

If the negotiated READY timer value indicates that the ready timer function is deactivated, the READY timer shall always run without expiry. If the negotiated READY timer value indicates that the ready timer function is deactivated, and within the same procedure the network indicates "force to standby" with the "force to standby" information element, the READY timer shall always run without expiry. If the negotiated READY timer value is set to zero, the READY timer shall be stopped immediately.

To account for the LLC frame uplink transmission delay, the READY timer value should be slightly shorter in the network than in the MS. This is a network implementation issue.

If a new READY timer value is negotiated, the MS shall upon the reception of the ATTACH ACCEPT or ROUTING AREA UPDATE ACCEPT message perform an initial cell update (either by transmitting a LLC frame or, if required, a ATTACH COMPLETE or ROUTING AREA UPDATE COMPLETE message), in order to apply the new READY timer value immediately. If both the network and the MS support the Cell Notification, the initial cell update shall use any LLC frame except the LLC NULL frame. If the new READY timer value is set to zero or if the network indicates "force to standby" with the "force to standby" IE, the initial cell update should not be done.

4.7.2.1.2 Handling of READY timer in the MS in Iu mode and S1 mode

The READY timer is not applicable for Iu mode in S1 mode.

Upon completion of a successful GPRS attach or routing area updating procedure in Iu mode, the MS shall stop the READY timer, if running.

Upon completion of a successful EPS attach or tracking area updating procedure, the MS shall stop the READY timer, if running.

In Iu mode, an MS may indicate a READY timer value to the network in the ATTACH REQUEST and the ROUTING AREA UPDATE REQUEST messages.

If a READY timer value is received by an MS capable of both Iu mode and A/Gb mode in the ATTACH ACCEPT or the ROUTING AREA UPDATE ACCEPT message, then the MS shall store the received value in order to use it at an intersystem change from Iu mode to A/Gb mode.

4.7.2.1.2a Handling of READY timer in the network in Iu mode and S1 mode

The READY timer is not applicable for Iu mode in S1 mode.

Upon completion of a successful GPRS attach or routing area updating procedure, the network shall stop the READY timer, if running.

When the SGSN is informed by the HLR/HSS that the MS performed an EPS attach or by the MME that the UE is performing a tracking area updating procedure, the SGSN shall stop the READY timer, if running.

4.7.2.2 Periodic routing area updating

The periodic routing area updating procedure is used to periodically notify the availability of the MS to the network. The procedure is controlled in the MS by timer T3312. The value of timer T3312 is sent by the network to the MS in the messages ATTACH ACCEPT and ROUTING AREA UPDATE ACCEPT. The value of timer T3312 shall be unique within a RA.

If the value of timer T3312 received by the MS in A/Gb mode or received in Iu mode in a message with integrity protection contains an indication that the timer is deactivated or the timer value is zero, then timer T3312 is deactivated and the MS shall not perform the periodic routing area updating procedure.

In Iu mode, if the value of timer T3312 is received in a message without integrity protection and the indicated value is larger than the last received value, or the indicated value is "deactivated" or zero, the MS shall use the last received value. If there is no last received value, then the MS shall use the default value.

In A/Gb mode, the timer T3312 is reset and started with its initial value, when the READY timer is stopped or expires. Timer T3312 is stopped and shall be set to its initial value for the next start when the READY timer is started. If after a READY timer negotiation the READY timer value is set to zero, timer T3312 is reset and started with its initial value. If the initial READY timer value is zero, the timer T3312 is reset and started with its initial value, when the ROUTING AREA UPDATE REQUEST message is transmitted.

In Iu mode, timer T3312 is reset and started with its initial value, when the MS changes from PMM-CONNECTED to PMM-IDLE mode. Timer T3312 is stopped when the MS enters PMM-CONNECTED mode.

If the MS is attached for emergency bearer services, when timer T3312 expires, the MS shall not initiate a periodic routing area updating procedure, but shall locally detach from the network. When the MS is camping on a suitable cell, it may re-attach to regain normal service.

If the MS is not attached for emergency bearer services, when timer T3312 expires, the periodic routing area updating procedure shall be started and timer T3312 shall be set to its initial value for the next start.

If the MS is in a state other than GMM-REGISTERED.NORMAL-SERVICE when timer T3312 expires, the periodic routing area updating procedure is delayed until the MS returns to GMM-REGISTERED.NORMAL-SERVICE.

In A/Gb mode, if the MS in MS operation mode B is in the state GMM-REGISTERED.SUSPENDED when timer T3312 expires the periodic routing area updating procedure is delayed until the state is left.

If ISR is activated, the MS shall keep both timer T3412 and timer T3312. The two separate timers run in the MS for updating the MME and the SGSN independently. The MS shall start timer T3323 if timer T3312 expires, and timer T3346 is running or the MS is in one of the following states:

– GMM-REGISTERED.NO-CELL-AVAILABLE;

– GMM-REGISTERED.PLMN-SEARCH;

– GMM-REGISTERED.UPDATE-NEEDED; or

– GMM-REGISTERED.LIMITED-SERVICE.

The MS shall initiate the routing area updating procedure and stop timer T3323 when the MS enters the state GMM-REGISTERED.NORMAL-SERVICE before timer T3323 expires. After expiry of timer T3323 the MS shall deactivate ISR by setting its TIN to "GUTI".

If timer T3323 expires, the MS shall memorize that it has to initiate a routing area updating procedure when it returns to state GMM-REGISTERED.NORMAL-SERVICE.

The network supervises the periodic routing area updating procedure by means of the mobile reachable timer.

If the MS is not attached for emergency bearer services, the mobile reachable timer shall be longer than timer T3312. In this case, by default, the mobile reachable timer is 4 minutes greater than timer T3312.

NOTE 1: According to subclause 4.7.5.1.5, if a periodic routing area updating procedure fails repeatedly, it can take more than 7 minutes before the MS starts using MM specific procedures.

The network may include timer T3312 extended value IE in the ATTACH ACCEPT message or ROUTING AREA UPDATE ACCEPT message only if the MS indicates support of the timer T3312 extended value in the MS network feature support IE.

If the network includes the timer T3312 extended value IE in the ATTACH ACCEPT message or ROUTING AREA UPDATE ACCEPT message, the network shall use the timer T3312 extended value IE as the value of timer T3312.

If ISR is not activated, when the mobile reachable timer expires, typically the network stops sending paging messages to the mobile and may take other appropriate actions.

If the MS is attached for emergency bearer services, the SGSN shall set the mobile reachable timer with a value equal to timer T3312. When the mobile reachable timer expires, the SGSN shall locally detach the MS.

In A/Gb mode, the mobile reachable timer is reset and started with the value as indicated above, when the READY timer is stopped or expires. The mobile reachable timer is stopped when the READY timer is started.

In A/Gb mode, if after a READY timer negotiation the READY timer value is set to zero, the mobile reachable timer is reset and started with its initial value. If the initial READY timer value is zero, the mobile reachable timer is reset and started with its initial value, when the ROUTING AREA UPDATE REQUEST message is received.

In Iu mode, the mobile reachable timer is reset and started with the value as indicated above, when the MS changes from PMM-CONNECTED to PMM-IDLE mode. The mobile reachable timer is stopped when the MS enters PMM-CONNECTED mode.

If ISR is activated, upon expiry of the mobile reachable timer the network shall start the implicit detach timer. By default, the implicit detach timer is 4 minutes greater than timer T3323. If the implicit detach timer expires before the MS contacts the network, the network shall implicitly detach the MS and deactivate ISR.

If ISR is not activated, upon expiry of the mobile reachable timer the network may start the implicit detach timer. The value of the implicit detach timer is network dependent. If the implicit detach timer expires before the MS contacts the network, the network shall implicitly detach the MS.

If the network includes the T3324 value IE in the ATTACH ACCEPT message or ROUTING AREA UPDATE ACCEPT message and if the MS is not attached for emergency bearer services and has no PDN connection for emergency bearer services, the network shall set the active timer to a value equal to the value of timer T3324.

If the MS has established a PDN connection for emergency bearer services after receiving the timer T3324 value IE in the ATTACH ACCEPT message or ROUTING AREA UPDATE ACCEPT message, the active timer shall not be started.

When the active timer expires, typically the network stops sending paging messages to the mobile and may take other appropriate actions.

In A/Gb mode, the active timer is reset and started with the value as indicated above, when the READY timer is stopped or expires. The active timer is stopped when the READY timer is started.

In Iu mode, the active timer is reset and started with the value as indicated above, when the MS changes from PMM-CONNECTED to PMM-IDLE mode. The active timer is stopped when the MS enters PMM-CONNECTED mode.

NOTE 2: ISR is not activated when the network includes the T3324 value IE in the ATTACH ACCEPT message or ROUTING AREA UPDATE ACCEPT message.

If the SGSN includes timer T3346 in the ROUTING AREA UPDATE REJECT message or the SERVICE REJECT message and timer T3346 is greater than timer T3312, the SGSN sets the mobile reachable timer and the implicit detach timer such that the sum of the timer values is greater than timer T3346.

NOTE 3: According to subclause 4.7.5.1.5, if a periodic routing area updating procedure fails repeatedly, it can take more than 7 minutes before the MS starts using MM specific procedures.

If the MS is both IMSI attached for GPRS and non-GPRS services, and if the MS lost coverage of the registered PLMN and timer T3312 expires or timer T3323 expires, then:

a) if the MS returns to coverage in a cell that supports GPRS and that indicates that the network is in network operation mode I, then the MS shall either perform the combined routing area update procedure indicating "combined RA/LA updating with IMSI attach"; or

b) if the MS returns to coverage in a cell in the same RA that supports GPRS and that indicates that the network is in network operation mode II, then the MS shall perform the periodic routing area updating procedure indicating "Periodic updating"; or

c) if the MS was both IMSI attached for GPRS and non-GPRS services in network operation mode I and the MS returns to coverage in a cell in the same LA that does not support GPRS, then the MS shall perform the periodic location updating procedure. In addition, the MS shall perform a combined routing area update procedure indicating "combined RA/LA updating with IMSI attach" when the MS enters a cell that supports GPRS and that indicates that the network is in network operation mode I; or

d) if the MS returns to coverage in a new RA, the description given in subclause 4.7.5 applies.

If this subclause specifies that the MS shall perform a periodic routing area updating procedure, but subclause 4.7.5 specifies the MS shall perform a normal or combined routing area updating procedure, the description in subclause 4.7.5 takes precedence.

If the MS is both IMSI attached for GPRS and non-GPRS services in a network that operates in network operation mode I, and if the MS has camped on a cell that does not support GPRS, and timer T3312 expires or timer T3323 expires, then the MS shall start an MM location updating procedure. In addition, the MS shall perform a combined routing area update procedure indicating "combined RA/LA updating with IMSI attach" when the MS enters a cell that supports GPRS and indicates that the network is in operation mode I.

If timer T3312 expires or timer T3323 expires during an ongoing CS connection, then a MS operating in MS operation mode B shall treat the expiry of T3312 when the MM state MM-IDLE is entered, analogous to the descriptions for the cases when the timer expires out of coverage or in a cell that does not support GPRS.

In A/Gb mode, timer T3312 and timer T3323 shall not be stopped when a GPRS MS enters state GMM-REGISTERED.SUSPENDED.

4.7.2.3 PMM-IDLE mode and PMM-CONNECTED mode (Iu mode only)

An MS shall enter PMM-CONNECTED mode when a PS signalling connection for packet switched domain is established between the MS and the network. The MS shall not perform periodic routing area update in PMM-CONNECTED mode.

An MS shall enter PMM-IDLE mode when the PS signalling connection for packet switched domain between the MS and the network has been released. The MS shall perform periodic routing area update in PMM-IDLE mode.

4.7.2.4 Handling of Force to standby in Iu mode (Iu mode only)

Force to standby is not applicable for Iu mode.

The network shall always indicate Force to standby not indicated in the Force to standby information element.

The Force to standby information element shall be ignored by the MS.

4.7.2.5 RA Update procedure for Signalling Connection Re-establishment (Iu mode only)

When the MS receives an indication from the lower layers that the RRC connection has been released with cause "Directed signalling connection re-establishment", see 3GPP TS 25.331 [23c] and 3GPP TS 44.118 [111], then the MS shall enter PMM-IDLE mode and initiate immediately a normal routing area update procedure (the use of normal or combined procedure depends on the network operation mode in the current serving cell) regardless whether the routing area has been changed since the last update or not. This routing area update procedure shall also be performed or continued if the MS has performed an inter-system change towards GSM, irrespective whether the READY timer is running or the MS is in PMM-IDLE or PMM-CONNECTED mode.

4.7.2.6 Cell Update triggered by low layers

A Cell Update may be requested by the low layers, see 3GPP TS 44.060 [76]. In this case the Cell Update shall be performed even if the READY timer is not running. If both the network and the MS support the Cell Notification, then the MS shall use the LLC NULL frame to perform the Cell Update.

4.7.2.7 Handling of timer T3302

The value of timer T3302 can be sent by the network to the MS in the ATTACH ACCEPT message, ROUTING AREA UPDATE ACCEPT message, ATTACH REJECT message, and ROUTING AREA UPDATE REJECT message. The MS shall apply this value, if the value is different from "deactivated" in the routing area registered by the MS, until a new value is received. The default value of this timer is used in the following cases:

– ATTACH ACCEPT message, ROUTING AREA UPDATE ACCEPT message, ATTACH REJECT message, or ROUTING AREA UPDATE REJECT message is received without a value specified;

– In Iu mode, if the network provides a value in a non-integrity protected Iu mode GMM message and the MS is not attaching for emergency services or not attached for emergency services;

– In A/Gb mode and if the MS supports integrity protection, if the network provides a value in a non-integrity protected GMM message;

– the network indicates that the timer is "deactivated";

– the MS does not have a stored value for this timer;

– a new PLMN which is not in the list of equivalent PLMNs has been entered, the routing area updating fails and the routing area updating attempt counter is equal to 5; or

– a new PLMN which is not in the list of equivalent PLMNs has been entered, the attach procedure fails, and the attach attempt counter is equal to 5.

4.7.2.8 Handling of timer T3324 (A/Gb mode, Iu mode and S1 mode)

An MS supporting PSM may request the network to assign a value for T3324 by including a requested timer value in:

– the ATTACH REQUEST or ROUTING AREA UPDATE REQUEST message (in A/Gb mode and Iu mode ); or

– the ATTACH REQUEST or TRACKING AREA UPDATE REQUEST message (in S1 mode).

The value of timer T3324 can be sent by the network to the MS in:

– the ATTACH ACCEPT or ROUTING AREA UPDATE ACCEPT message (in A/Gb mode and Iu mode ); and

– the ATTACH ACCEPT or TRACKING AREA UPDATE ACCEPT message (in S1 mode).

NOTE: Besides the value requested by the MS, the network can take local configuration into account when selecting a value for T3324 (see 3GPP TS 23.682 [133A], subclause 4.5.4).

In A/Gb mode and Iu mode, the MS shall apply the received T3324 value in the RA identified by the RAI contained in the ATTACH ACCEPT or ROUTING AREA UPDATE ACCEPT message, until a new value is received, T3324 is deactivated or a new PLMN is selected. The timer T3324 is deactivated if:

– the last attach or routing area updating attempt was not completed successfully;

– the network does not include a value for timer T3324 in the last ATTACH ACCEPT or ROUTING AREA UPDATE ACCEPT message received by the MS; or

– the indicated value of the timer is "deactivated".

In A/Gb mode and Iu mode, timer T3324 is reset and started with its initial value, when the MS changes from PMM-CONNECTED mode to PMM-IDLE mode (in Iu mode) or when the READY timer is stopped or expires (in A/Gb mode). Timer T3324 is stopped when the MS enters PMM-CONNECTED mode or GMM-DEREGISTERED state or the READY timer is started.

In S1 mode, the MS shall apply the received T3324 value in all tracking areas of the list of tracking areas assigned to the MS, until a new value is received, T3324 is deactivated or a new PLMN is selected. The timer T3324 is deactivated if:

– the last attach or tracking area updating attempt was not completed successfully;

– the network does not include a value for timer T3324 in the last ATTACH ACCEPT or TRACKING AREA UPDATE ACCEPT message received by the MS; or

– the indicated value of the timer is "deactivated".

In S1 mode, timer T3324 is reset and started with its initial value, when the MS changes from EMM-CONNECTED mode to EMM-IDLE mode. Timer T3324 is stopped when the MS enters EMM-CONNECTED mode or EMM-DEREGISTERED state.In A/Gb mode and Iu mode, when timer T3324 expires the MS may activate PSM as specified in subclause 4.7.2.9.

In S1 mode, when timer T3324 expires the MS may activate PSM as specified in 3GPP TS 24.301 [120], subclause 5.3.11.

In A/Gb mode and Iu mode, if timer T3324 expires during an ongoing CS connection, the MS shall take action on the expiry of timer T3324 as described in subclause 4.7.2.9 when the MM state MM-IDLE is entered.

4.7.2.9 Power saving mode

The MS can request the use of power saving mode (PSM) during an attach or routing area updating procedures (see 3GPP TS 23.682 [133A] and 3GPP TS 23.060 [74]). The MS shall not request the use of PSM during:

– an attach for emergency bearer services procedure;

– a routing area updating procedure for initiating a PDN connection for emergency bearer services; or

– a routing area updating procedure when the MS has a PDN connection established for emergency bearer services.

The network accepts the use of PSM by providing a specific value for timer T3324 when accepting the attach or routing area updating procedure. The MS may use PSM only if the network has provided the T3324 value IE during the last attach or routing area updating procedure with a value different from "deactivated".

Upon expiry of the timer T3324 or if the T3324 value provided by the network is zero, the MS may deactivate the AS layer and activate PSM by entering the state GMM-REGISTERED.NO-CELL-AVAILABLE if:

a) the MS is not attached for emergency bearer services;

b) the MS has no PDN connection for emergency bearer services;

c) the MS is in PMM-IDLE mode (in Iu mode) or the READY timer is not running (in A/Gb mode);

d) the MS is in the GMM-REGISTERED.NORMAL-SERVICE state; and

e) no RR connection exists.

If conditions a, b, c and e are fulfilled, but the MS is in a state other than GMM-REGISTERED.NORMAL-SERVICE when timer T3324 expires, the MS may activate PSM when the MS returns to state GMM-REGISTERED.NORMAL-SERVICE.

If conditions a, b, c and d are fulfilled, but an RR connection exists, the MS may activate PSM when the RR connection has been released.

An MS that has already been allocated timer T3324 with a value different from "deactivated" and the timer T3324 has expired, may activate PSM if it receives an "Extended wait time" from lower layers.

When PSM is activated all NAS timers are stopped and associated procedures aborted except for timers T3312, T3346, T3396, any backoff timers, and the timer T controlling the periodic search for HPLMN or EHPLMN (if the EHPLMN list is present) or higher prioritized PLMNs (see 3GPP TS 23.122 [14]).

If the MS is attached for emergency bearer services or has a PDN connection for emergency bearer services, the MS shall not activate PSM.

The MS may deactivate PSM at any time (e.g. for transfer of mobile originated signalling or user data, or to initiate a mobile originated circuit-switched transaction), by activating the AS layer before initiating the necessary GMM or MM procedures (if any).

4.7.2.10 Extended idle-mode DRX cycle

The MS can request the use of extended idle mode DRX cycle (eDRX) during an attach or routing area updating procedure by including the extended DRX parameters IE (see 3GPP TS 23.682 [11A] and 3GPP TS 23.060 [74]). The MS shall not request the use of eDRX during:

– an attach for emergency bearer services procedure; or

– a routing area updating procedure for the MS attached for emergency bearer services.

The MS and the network may negotiate eDRX parameters during a routing area updating procedure when the MS has a PDP context for emergency bearer services.

The network accepts the request to use eDRX by providing the extended DRX parameters IE when accepting the attach or the routing area updating procedure. The MS shall use extended idle mode DRX cycle only if it received the extended DRX parameters IE during the last attach or routing area updating procedure and the MS does not have a PDP context for emergency bearer services.

NOTE: If the MS wants to keep using eDRX, the MS includes the extended DRX parameters IE in each attach or routing area updating procedure.

If the MS received the extended DRX parameters IE during the last attach or routing area updating procedure, upon the successful completion of the PDP context deactivation procedure for a PDP context for emergency bearer services, the MS shall resume eDRX.

If the network has provided the extended DRX parameters IE during the last attach or routing area updating procedure, upon the successful completion of the PDP context deactivation procedure for a PDP context for emergency bearer services, the network shall resume eDRX.

If the MS or the network locally deactivates the PDP context for emergency bearer service, the MS or the network shall not use eDRX until the MS receives eDRX parameters during a routing area updating procedure with PDP context synchronization or upon successful completion of a service request procedure.

If the MS did not receive the extended DRX parameters IE, or if the MS has a PDP context for emergency bearer services, the MS shall use the stored DRX parameters, if available.

If the network did not accept the request to use eDRX, or if the MS has a PDP context for emergency bearer services, the network shall use the stored DRX parameters, if available.

4.7.2.11 Interaction between power saving mode and extended idle mode DRX cycle

The MS can request the use of both PSM and eDRX during an attach or routing area update procedure but it is up to the network to decide to enable none, one of them or both (see 3GPP TS 23.682 [133A] and 3GPP TS 23.060 [74]).

If the network accepts the use of both PSM (see subclause 4.7.2.9) and eDRX (see subclause 4.7.2.10), the extended DRX parameters IE provided to the MS should allow for multiple paging occasions before the active timer expires.

4.7.2.12 Extended coverage for GSM

The MS can support and use the extended coverage in GSM for IoT (EC-GSM-IoT) feature (see 3GPP TS 43.064 [159]). A GPRS MS using EC-GSM-IoT may operate in MS operation mode C only. If the MS uses one of the four coverage classes of EC-GSM-IoT as defined in 3GPP TS 43.064 [159], the MS shall calculate the value of the applicable NAS timers as indicated in tables 11.3, 11.3A and 11.2c using a multiplier of 3, unless the timer is deactivated. The NAS timer value obtained is used as described in the appropriate procedure subclause of this specification. The NAS timer value shall be calculated at start of a NAS procedure and shall not be re-calculated until the NAS procedure is completed, restarted or aborted.

The usage of one of the four coverage classes of EC-GSM-IoT by an MS is indicated to the SGSN by lower layers. When a SGSN that supports EC-GSM-IoT performs NAS signaling with an MS that is using EC-GSM-IoT, the SGSN shall calculate the value of the applicable NAS timers as indicated in tables 11.4, 11.4a and 11.2d using a multiplier of 3. The NAS timer value shall be calculated at start of a NAS procedure and shall not be re-calculated until the NAS procedure is completed, restarted or aborted.

In order to deal with use of extensive resources from the network, the operator may prevent specific subscribers from using enhanced coverage (see 3GPP TS 23.060 [74]). When in A/Gb mode, the MS supporting EC-GSM-IoT shall indicate support for restriction on use of enhanced coverage. The MS supporting restriction on use of enhanced coverage indicates "Mobile station supports restriction on use of enhanced coverage" in the MS network capability information element in the ATTACH REQUEST and ROUTING AREA UPDATE REQUEST message. If the MS supports restriction on use of enhanced coverage, the SGSN indicates whether the use of enhanced coverage is restricted or not in the ATTACH ACCEPT message and ROUTING AREA UPDATE ACCEPT message (see subclause 4.7.3.1 and subclause 4.7.5.1). If the use of enhanced coverage is restricted the MS shall not use enhanced coverage in the registered PLMN and in any PLMN which is in the list of equivalent PLMNs.