UE-initiated Idle to Active Transition
The following call flow depicts the UE-initiated idle to active transition.

Step | Description |
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1 |
The AMF requests SMF to activate the user plane connection of the PDU session by sending a POST request with the following information:
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2 |
Upon receipt of the request, the SMF starts activating the N3 tunnel of the PDU session. The SMF returns a 200 OK response with the following information:
|
3 |
Subsequently, the AMF requests the SMF by sending POST request with the following information:
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4 |
The SMF initiates PFCP Session Modification Procedure towards UPF with down link FAR updated with the following options:
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5 | Upon receipt of successful response from UPF node, the SMF sets the upCnxState attribute to ACTIVATED for the PDU session. |
6 | SMF then initiates 200 OK response including the upCnxState attribute set to ACTIVATED towards AMF. |