Network-requested PDU Session Modification Call Flow
This section describes the network-requested PDU session modification procedure in which the Always-on PDU session indication is sent.
The following figure illustrates the network-requested PDU Session Modification call flow.

| Step | Description |
|---|---|
| 1 |
The SMF decides to trigger a PDU Session Modification due to PCF, UDM, or RAN initiated procedures. |
| 2 |
The SMF checks the DNN profile to determine whether the always-on support is enabled. |
| 3 |
The SMF determines whether the current DNN configuration for always-on is different from the last indication sent to UE. If it differs, the SMF includes the "Always-on PDU Session Indication" IE in the PDU Session Modification Command message. |