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the unauthenticated IMSI is retained in the network for recording purposes. The IMEI is used in<br />
the network to identify the UE.<br />
When a UE attaches to the network, indication is provided to the UE if emergency bearer services are<br />
supported in the network. UEs in limited service state determine whether the cell supports emergency<br />
services over E-UTRAN from a broadcast indicator in Access Stratum.<br />
To provide emergency bearer services independent of subscription, the MME is configured with MME<br />
Emergency Configuration Data, which are applied to all emergency bearer services that are established<br />
by an MME on UE request. The MME Emergency Configuration Data contain the Emergency Access<br />
Point Name (APN), which is used to derive a PDN GW, or the MME Emergency Configuration Data may<br />
also contain the statically configured PDN GW for the Emergency APN.<br />
B.2.1.1 MOBILITY AND ACCESS RESTRICTIONS FOR EMERGENCY SERVICES<br />
When emergency services are supported and local regulation requires emergency calls to be provided<br />
regardless of mobility or access restrictions, the mobility restrictions should not be applied to UEs<br />
receiving emergency services. The source E-UTRAN ignores any mobility and access restrictions during<br />
handover evaluation when there are active emergency bearers.<br />
During Tracking Area Update procedures, the target MME ignores any mobility or access restrictions for<br />
UE with emergency bearer services where required by local regulation. When a UE moves into a target<br />
location that is not allowed by subscription, any non-emergency bearer services are deactivated by the<br />
target MME.<br />
B.2.1.2 HANDOVER AND SINGLE RADIO VOICE CALL CONTINUITY SUPPORT<br />
Handover and SRVCC support of emergency bearer is provided for the following radio access types:<br />
� Handover to and from UTRAN (HSPA)<br />
� Handover to non-3GPP HRPD access on EPC<br />
� SRVCC to 3GPP UTRAN and GERAN in the CS domain<br />
� SRVCC to 3GPP2 CDMA 1x in the CS domain<br />
In order to support IMS session continuity (i.e. SRVCC) of emergency sessions, the IMS emergency<br />
services architecture is enhanced with an Emergency Access Transfer Function (EATF) used to anchor<br />
the IMS emergency session in the local serving network and manage access transfer of an emergency<br />
session to the CS domain.<br />
B.2.1.3 REACHABILITY MANAGEMENT FOR UE WHEN I<strong>DL</strong>E<br />
In order to support efficient re-establishment of an IMS emergency session or call back from a PSAP, the<br />
emergency bearer service PDN connection remains active for a configurable time after the end of the IMS<br />
emergency session.<br />
www.4gamericas.org February 2011 Page 114
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