Section: 4.3.27a Restriction of use of Enhanced Coverage for voice centric UE
Content: Support of UEs in Enhanced Coverage is specified in TS 36.300[ Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 ]  [5]. If the UE's usage setting is "voice centric" as defined in TS 23.221[ Architectural requirements ]  [27], it shall not operate in CE mode B. If the UE supports CE mode B and UE's usage setting is set to "voice centric" in the Attach or TAU request message then the MME shall indicate to eNodeB that CE mode B is restricted. If the UE supports CE mode B and UE's usage setting is set to "data centric" in the Attach or TAU request message then, based on operator's policy and the Enhanced Coverage Restricted parameter (see clause 4.3.28), the MME shall indicate to eNodeB that CE mode B is not restricted. The MME keeps the CE mode B Restricted parameter in the MM Context. The MME shall send the CE mode B Restricted parameter to the eNodeB via S1 signalling indicating whether the UE is "restricted" or "not restricted" for the use of CE mode B, e.g. in PAGING, INITIAL CONTEXT SETUP REQUEST, HANDOVER REQUEST, PATH SWITCH REQUEST ACKNOWLEDGE, CONNECTION ESTABLISHMENT INDICATION, and DOWNLINK NAS TRANSPORT message carrying the TAU ACCEPT message. If the UE supports CE mode B and the CE mode B Restricted parameter stored in the MME's MM context is set to "not restricted", the MME shall use the extended NAS timer settings for the UE as specified in TS 24.301[ Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 ]  [46].