E.3 Reporting EPS Fallback

29.2143GPPPolicy and charging control over Rx reference pointRelease 17TS

When the feature "EPSFallbackReport" is supported, if the AF requests the PCF to report EPS Fallback, the AF shall subscribe to the "EPS_FALLBACK" within the Specific-Action AVP as described in clause 5.3.13. The AF shall request the PCF to report the EPS Fallback in conjuction with providing the PCF with the AF session information as described in clause 4.4.1 for the initial provisioning of session information, and the subscription to "EPS_FALLBACK" shall apply for voice media type requests along the AF session lifetime.

When the PCF then receives the EPS Fallback indication from the SMF, the PCF shall provide the corresponding EPS Fallback indication to the AF by sending an RAR (re-authorization request) command. The RAR command shall include the EPS_FALLBACK cause encoded in the Specific-Action AVP.

When the AF receives the RAR command, it shall acknowledge the command by sending an RAA (re-authorization answer) command to the PCF.