Section: 4.3.18.4 CS fallback
Content: CS Fallback allows users to fallback to GERAN/UTRAN/1x RTT while in E-UTRAN access thus allowing the network to transfer the call towards GERAN/UTRAN CS domain. In order to ensure that a priority CSFB call to/from a service user is given proper priority treatment in the EPS, MPS subscription indicates the user's CS priority status, i.e. MPS CS Priority, which is provided to MME with user's subscription information. When the eNodeB receives mobile initiated signalling with establishment cause set to highPriorityAccess, the eNodeB handles the RRC connection request with priority. When the MME receives and verifies mobile initiated signalling with establishment cause set to highPriorityAccess, the MME establishes the S1 bearer with priority. Details on the priority treatment of CSFB, see TS 23.272[ Circuit Switched (CS) fallback in Evolved Packet System (EPS); Stage 2 ]  [58].