Section: 4.7.2.12 Extended coverage for GSM
Content: The MS can support and use the extended coverage in GSM for IoT (EC-GSM-IoT) feature (see 3GPP TS 43.064[ None ]  [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[ None ]  [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[ General Packet Radio Service (GPRS); Service description; Stage 2 ]  [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.