This isn't something you call — it documents the redirect Fusion sends the respondent's browser to once the buyer reports an outcome, so you know what to expect on the receiving end.
Fusion redirects to whichever of your configured URLs matches the outcome: Complete, Terminate, Quota full, Quality fail, or Security fail. Any custom fields you mapped (respondent, click, or member ID) are appended automatically. If server-to-server postbacks are enabled for your account, Fusion also fires the same outcome to a URL you registered, independent of whether the browser redirect completes.