PHASE 3
In Phase 3 (or first scheduled UL transmission), the UE provides the network with a unique identifier in the message. It transmits on Uplink shared channel (UL-SCH) according to the grant contained in the RA Response. The type of UE identifier, e.g. C-RNTI, TMSI, IMSI or IMEI, depends on which extent the UE is already known in the network.