The purpose of the service request procedure is to transfer the EMM mode from EMM-IDLE to EMM-CONNECTED
mode and establish the radio and S1 bearers when uplink user data or signalling is to be sent. Another purpose of this
procedure is to invoke MO/MT CS fallback or 1xCS fallback procedures.
This procedure is used when:
– the network has downlink signalling pending;
– the UE has uplink signalling pending;
– the UE or the network has user data pending and the UE is in EMM-IDLE mode;
– the UE in EMM-IDLE or EMM-CONNECTED mode has requested to perform mobile originating/terminating
CS fallback or 1xCS fallback;
The service request procedure is initiated by the UE, however, for the downlink transfer of signalling, cdma2000®
signalling or user data in EMM-IDLE mode, the trigger is given by the network by means of the paging procedure
The UE shall invoke the service request procedure when:
a) the UE in EMM-IDLE mode receives a paging request with CN domain indicator set to “PS” from the network;
b) the UE, in EMM-IDLE mode, has pending user data to be sent;
c) the UE, in EMM-IDLE mode, has uplink signalling pending;
d) the UE in EMM-IDLE or EMM-CONNECTED mode is configured to use CS fallback and has a mobile
originating CS fallback request from the upper layer;
e) the UE in EMM-IDLE mode is configured to use CS fallback and receives a paging request with CN domain
indicator set to “CS”, or the UE in EMM-CONNECTED mode is configured to use CS fallback and receives a
CS SERVICE NOTIFICATION message;
f) the UE performs an inter-system change from S101 mode to S1 mode and has user data pending.