Nta (application id: 16777358)

The Nta interface facilitates communication between the Policy and Charging Rules Function (PCRF) and the Service Capability Exposure Function (SCEF). The Nta interface is specifically designed for configuring event monitoring for a group of User Equipment (UEs) and reporting those events. 

Nta interface workflow

1. Event Configuration Request:
   • The process begins when the SCEF receives a request from an SCS/AS to monitor specific events, such as location changes, for a group of UEs.
   • The SCEF sends an Event-Configuration-Request (ECR) command to the PCRF. This request includes various Attribute-Value Pairs (AVPs), such as Monitoring-Type, External-Group-Identifier, and others that specify the details of the monitoring configuration.
2. Event Configuration Answer:
   • Upon receiving the ECR, the PCRF retrieves the necessary UE identities and checks for any active IP-CAN sessions related to those UEs.
   • The PCRF responds with an Event-Configuration-Answer (ECA) command, which indicates whether the event monitoring configuration was successfully applied. If successful, the PCRF proceeds to monitor the specified events based on the configuration.
3. Event Reporting:
   • When an event that matches the configured monitoring parameters occurs, the PCRF generates a report and sends it to the SCEF using the Nta interface.
   • The SCEF then forwards this event report to the requesting SCS/AS, completing the monitoring and reporting cycle.

For complete technical specification of Nta interface in Diameter protocol please refer to: [3GPP TS 29.154]