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    - Verify that if IUT receives a SERVICE REQUEST message or a CONTROL PLANE SERVICE REQUEST message before the network-initiated de-registration procedure has been completed (e.g. the DEREGISTRATION REQUEST message is pending to be sent to the UE), the network shall progress the de-registration procedure.

## 6.4.1.3 UE-requested PDU session establishment procedure accepted by the network (FF)

 - Verify that the IUT, upon receiving the PDU SESSION ESTABLISHMENT REQUEST from the UE with correct data and with type initial request, sends PDU SESSION ESTABLISHMENT ACCEPT meesage

## 6.4.1.7 Abnormal cases on the network side (FF)

 - Verify that the IUT sends a PDU SESSION ESTABLISHMENT REJECT with cause #31 (request rejected, unspecified), when the UE sends a PDU SESSION ESTABLISHMENT REQUEST with type initial emergency request and there is already a emergency PDU session for the UE.

Note: possible, that the IUT releases the existing emergency session and don't sends a REJECT. Maybe implementation-dependend?

 - Verify that the IUT sends a PDU SESSION ESTABLISHMENT REJECT with cause #54 (PDU session does not exist), when the UE sends a PDU SESSION ESTABLISHMENT REQUEST with type existing PDU session and there is no PDU session with that ID.

 - Verify that the IUT sends a PDU SESSION ESTABLISHMENT REJECT with cause #29 (user authentication or authorization failed), when the UE sends a PDU SESSION ESTABLISHMENT REQUEST with type initial request and the provided authentication and authorization data don't match local policy and user's subscription data.

## 6.3.1.1 (FF)

- Verify that the IUT, upon receiving the PDU SESSION AUTHENTICATION COMPLETE Message after completing the PDU session authentication and authorization procedure, successfully completes the  process by sending PDU SESSION ESTABLISHMENT ACCEPT.

 - Verify that the IUT aborts the procedure after timer T3590 expiration four times.

## 6.4.3.2 (FF)

## 6.4.3.2, 6.4.3.4 (FF)

 - Verify that the IUT handles correctly a PDU SESSION RELEASE REQUEST after receiving a PDU SESSION RELEASE REQUEST by the UE.

 Note: There is no message back to the UE after receiving the PDU SESSION RELEASE REJECT, the correct execution of Session Release can be tested with another message.

 - Verify that the IUT sends correctly a PDU SESSION RELEASE REJECT after receiving a PDU SESSION RELEASE REQUEST by the UE and not accepts the session release with reason #43 (Invalid PDU session identity).

 Note: there can be other protocol reasons for not accepting the PDU Session release

 ## 6.4.3.6 (FF)

 - Verify that the IUT sends correctly a PDU SESSION RELEASE REJECT after receiving a PDU SESSION RELEASE REQUEST with a wrong PDU Sesiion ID by the UE and not accepts the session release with reason #43 (Invalid PDU session identity).