Application triggering for a wireless device

1. A method comprising:

receiving, by a session management function (SMF) from a network exposure function (NEF), a request message for delivering a trigger to a wireless device, the request message comprising:

a trigger payload comprising information, for an application on the wireless device, indicating a request to establish a packet data unit (PDU) session; and

a trigger indication identifying that the request message carries the trigger payload;

sending, by the SMF to the wireless device via an access and mobility management function (AMF), a non-access stratum (NAS) message comprising:

the trigger indication; and

the trigger payload; and

receiving, by the SMF from the wireless device via the AMF and based on the trigger payload, a session establishment request to establish the PDU session for the application.

2. The method of claim 1 , further comprising:

sending, by the SMF to the NEF and based on the received request, a connection request to establish the PDU session for the application.

3. The method of claim 1 , wherein the request message comprises an identifier of the wireless device.

4. The method of claim 1 , further comprising:

receiving, by the SMF from the wireless device, a confirmation message indicating a delivery of the trigger to the wireless device.

5. The method of claim 1 , further comprising:

sending, by the SMF to the AMF, a reachability request message to request whether the wireless device identified by an identifier is reachable; and

receiving, by the SMF from the AMF, a response message indicating that the wireless device having the identifier is reachable.

6. The method of claim 1 , further comprising:

sending, by the SMF to a unified data management (UDM), a reachability request message to request whether the wireless device identified by an identifier is reachable; and

receiving, by the SMF from the UDM, a response message indicating that the wireless device having the identifier is reachable.

7. The method of claim 1 , further comprising:

selecting, by the SMF, a user plane function (UPF) for a session;

sending, by the SMF to the UPF, the session establishment request; and

receiving, by the SMF from the UPF, a session establishment response message.

8. The method of claim 1 , wherein the NAS message comprises a session management non-access stratum (SM-NAS) message.

9. The method of claim 1 , wherein the information comprises an identifier of the application on the wireless device.

10. A session management function (SMF) comprising:

one or more processors; and

memory storing instructions that, when executed by the one or more processors, cause the session management function to:

receive, from a network exposure function (NEF), a request message for delivering a trigger to a wireless device, the request message comprising:

a trigger payload comprising information, for an application on the wireless device, indicating a request to establish a packet data unit (PDU) session; and

a trigger indication identifying that the request message carries the trigger payload;

send, to the wireless device via an access and mobility management function (AMF), a non-access stratum (NAS) message comprising:

the trigger indication; and

the trigger payload; and

receive, from the wireless device via the AMF and based on the trigger payload, a session establishment request to establish PDU session for the application.

11. The SMF of claim 10 , wherein the instructions further cause the SMF to:

send, to the NEF and based on the received request, a connection request to establish the PDU session for the application.

12. The SMF of claim 10 , wherein the request message comprises an identifier of the wireless device.

13. The SMF of claim 10 , wherein the instructions further cause the SMF to:

receive, from the wireless device, a confirmation message indicating a delivery of the trigger to the wireless device.

14. The SMF of claim 10 , wherein the instructions further cause the SMF to:

send, to the AMF, a reachability request message to request whether the wireless device identified by an identifier is reachable; and

receive, from the AMF, a response message indicating that the wireless device having the identifier is reachable.

15. The SMF of claim 10 , wherein the instructions further cause the SMF to:

send, to a unified data management (UDM), a reachability request message to request whether the wireless device identified by an identifier is reachable; and

receive, from the UDM, a response message indicating that the wireless device having the identifier is reachable.

16. The SMF of claim 10 , wherein the instructions further cause the SMF to:

select a user plane function (UPF) for a session;

send the session establishment request to the UPF; and

receive a session establishment response message from the UPF.

17. The SMF of claim 10 , wherein the NAS message comprises a session management non-access stratum (SM-NAS) message.

18. A system comprising:

a session management function (SMF) comprising: one or more first processors and first memory storing instructions that, when executed by the first one or more processors, cause the SMF to:

receive, from a network exposure function (NEF), a request message for delivering a trigger to a wireless device, the request message comprising:

a trigger payload comprising information, for an application on the wireless device, indicating a request to establish a packet data unit (PDU) session; and

a trigger indication identifying that the request message carries the trigger payload;

send, to the wireless device via an access and mobility management function (AMF), a non-access stratum (NAS) message comprising:

the trigger indication; and

the trigger payload; and

receive, from the wireless device via the AMF and based on the trigger payload, a session establishment request to establish the PDU session for the application; and

the AMF, wherein the AMF comprises: one or more second processors and second memory storing instructions that, when executed by the one or more second processors, cause the AMF to:

send, to the wireless device, the NAS message received from the SMF; and

send, to the SMF, the session establishment request received from the wireless device.