Cause determination for terminated calls in a 5G network

1 . A method comprising:

receiving, by a server of a fifth generation (5G) telecommunications network, a message indicating a request to terminate a communication session associated with a user equipment (UE), wherein the message is a Npcf_PolicyAuthorization_delete message;

determining, by the server, that the message is associated with a Policy Authorization Service implemented by a Policy Control Function (PCF);

determining, by the server, a value representing a cause for the communication session to terminate;

modifying, by the server and as a modified message, the message to include a field identifying the cause for the communication session to terminate; and

transmitting, by the server, the modified message to a network function of the 5G telecommunications network,

wherein the server provides an application function (AF) and the network function includes the PCF.

2 . The method of claim 1 , wherein determining that the message is associated with the Policy Authorization Service comprises identifying that that the message is an Npcf service-based message.

3 . The method of claim 1 , wherein the modified message is transmitted using an N5 interface.

4 . The method of claim 1 , wherein:

the AF comprises a proxy call session control function (PCSCF) associated with an Internet Protocol (IP) Multimedia Subsystem (IMS).

5 . The method of claim 1 , wherein:

the message is a first message, and

determining the value representing the cause for the communication session to terminate comprises identifying a text value in a second message associated with the server.

6 . The method of claim 5 , wherein the second message is a Session Initiation Protocol message or a message sent in association with an Rx interface.

7 . The method of claim 1 , wherein the value is a Termination-Cause AVP Value.

8 . The method of claim 1 , wherein the value is associated with a first amount of data and further comprising:

determining, in the field, a second amount of data to represent the cause for the communication session to terminate, the second amount of data less than the first amount of data; and

adding the second amount of data to the field of the modified message.

9 . The method of claim 1 , wherein determining the value representing the cause for the communication session to terminate comprises:

identifying first text associated with the cause for the communication session to terminate from another message associated with the server;

modifying the first text to output second text different from the first text; and

outputting the second text as the value representing the cause for the communication session to terminate.

10 . The method of claim 1 , wherein modifying the message to include the field identifying the cause for the communication session to terminate comprises concatenating the value representing the cause with the message.

11 . A system comprising:

one or more processors; and

memory storing computer-executable instructions that, when executed by the one or more processors, cause the system to perform operations comprising:

configuring, by a server of a fifth generation (5G) telecommunications network, a Policy Authorization Service message for sending to a Policy Control Function (PCF), the Policy Authorization Service message indicating a request to terminate a communication session, the configuring including:

determining to send the Policy Authorization Service message using an N5 interface;

identifying a value representing a cause for the communication session to terminate;

adding the value to the Policy Authorization Service message; and

sending, by the server, the Policy Authorization Service message with the value to the PCF,

wherein the server provides an application function (AF) that comprises a proxy call session control function (PCSCF) associated with an Internet Protocol (IP) Multimedia Subsystem (IMS).

12 . The system of claim 11 , wherein:

identifying the value representing the cause for the communication session to terminate comprises identifying a text value in a message different from the Policy Authorization Service message.

13 . The system of claim 11 , wherein adding the value comprises:

modifying the Policy Authorization Service message to include a field identifying the cause for the communication session to terminate; and

adding the value to the field.

14 . The system of claim 11 , the operations further comprising:

determining, based at least in part on the value, whether the cause for the communication session to terminate is an expected result or an unexpected result; and

determining performance of the 5G telecommunications network based at least in part on a number of unexpected results over time.

15 . One or more non-transitory computer-readable media storing instructions executable by one or more processors, wherein the instructions, when executed, cause the one or more processors to perform operations comprising:

receiving, by a server of a telecommunications network, a message indicating a request to terminate a communication session associated with a user equipment (UE), wherein the message is a Npcf_PolicyAuthorization_delete message;

determining, by the server, that the message is associated with a Policy Authorization Service implemented by a Policy Control Function (PCF);

determining, by the server, a value representing a cause for the communication session to terminate;

modifying, by the server and as a modified message, the message to include a field identifying the cause for the communication session to terminate; and

transmitting, by the server, the modified message to a network function of the telecommunications network,

wherein the server provides an application function (AF) and the network function includes the PCF.

16 . The one or more non-transitory computer-readable media of claim 15 , wherein determining that the message is associated with the Policy Authorization Service comprises identifying that that the message is an Npcf service-based message.

17 . The one or more non-transitory computer-readable media of claim 15 , wherein the modified message is transmitted using an N5 interface.

18 . The one or more non-transitory computer-readable media of claim 15 , wherein the AF comprises a proxy call session control function (PCSCF) associated with an Internet Protocol (IP) Multimedia Subsystem (IMS).