# UE Registration Call Flow


## Step-by-step

#### a. RAN detecting new UE and send notification to AMF

#### b. AMF requesting NAS Identification request to UE for authentication purpose

#### c. AMF send an authentication request to AUSF

#### d. AUSF communicate with UDM for UE authentication data

#### e. AUSF generate authentication key (5GAKA) and send the key to AMF

#### f. AMF forward the key to UE

#### g. AMF communicate with UDM to retrieve user network slice, AM subscription and SM data

#### h. AMF discover PCF through NRF and retrieve applicable policies for authenticated UE

#### i. AMF communicate with NSSF to select appropriate SMF

#### j. AMF communicate with selected SMF to generate PDU session based on data received by AMF from PCF

#### k. SMF request a tunneling session to UPF to handle data transmission between UE and DN, SMF will control UPF based on defined policies in PCF.

#### l. Data transported from DN to UE and vice versa