PDU Session Establishment Reject
If the connectivity with the requested DN is rejected by the network, SMF sets the 5GSM cause IE of the PDU Session Establishment Reject message to indicate the reason for rejecting the PDU Session Establishment procedure.
The SMF supports the following causes in the PDU Session Establishment Reject message.
Reject Cause / 5GSM Cause |
SMF Behavior |
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Cause #26 – insufficient resources |
The SMF includes this cause when it receives N2SmInfoType with "PDU_RES_SETUP_FAIL" along with any of the following N2 causes:
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Cause #27 – missing or unknown DNN |
The SMF includes this cause when DNN is not present in SmContextCreateData even though it is required and not configured in SMF. |
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Cause #28 – unknown PDU session type |
The SMF includes this cause when the PDU Session Establishment Request message includes a PDU session type that is not supported by SMF. |
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Cause #29 – user authentication or authorization failed |
The SMF includes this cause when DN authentication of the UE was performed and completed unsuccessfully (Radius Authentication Timeout). |
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Cause #32 – service option not supported |
The SMF supports this cause when the validation of received S-NSSAI fails against the allowed list of S-NSSAI. |
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Cause #33 – requested service option not subscribed |
The SMF supports this cause when the UE requests a service option for which it has no subscription. |
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Cause #38 – network failure |
The SMF supports this cause when the requested service was rejected due to an error in the network. This includes any internal failures or no response from any external NF during the PDN-setup procedure. |
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Cause #54 – PDU session does not exist |
The SMF supports this cause when it does not have any information about the PDU session which is requested by the UE to transfer between 3GPP access and non-3GPP access or from the EPS to the 5GS. |
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Cause #70 – missing or unknown DNN in a slice |
The SMF supports this cause when the slice configuration is present but the requested DNN is not configured under the slice in the SMF. |
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Protocol errors |
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Cause #95 – Semantically incorrect message |
This 5GSM cause reports receipt of a message with semantically incorrect content.
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