How it Works
In the Dummy N7 Notify Request feature, the PCF interactions happen in the following sequence:
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The SMF sends an N7 Create Request to PCF. The PCF responds to this request with the configured event triggers.
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When IMS initiates multimedia calls containing the AAR message with the Media-Type, PCF initiates an N7 Notify Request to assign the PCC rules that are evaluated based on the media details received in the AAR message. However, in some situations PCF cannot compute the rules as it did not subscribe to the specific event triggers such as RAT-Change and AccessType AVP.
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The PCF attempts to determine the corresponding event trigger from the SMF by sending an intermediate (dummy) N7 Notify Request to SMF.
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The SMF responds with the applicable event triggers that are specified in the dummy N7 request.
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The PCF uses these triggers to compute the PCC rules and transmits it to the SMF in the subsequent N7 Notify Request.