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# fail()

Reports the failed execution of the action.

```
func fail()
```

## Discussion

Calling this method sets the [`isComplete`](/documentation/CallKit/CXAction/isComplete) property value to <doc://com.apple.documentation/documentation/Swift/true>. Calling this method more than once or calling it after calling the [`fulfill()`](/documentation/CallKit/CXAction/fulfill()) method has no effect.

It’s safe to call `fail()` asynchronously. For example, call it in [`CXProviderDelegate`](/documentation/CallKit/CXProviderDelegate) callback method implementations as shown in the following code snippet from the [Making and receiving VoIP calls](/documentation/CallKit/making-and-receiving-voip-calls) sample code project:

```swift
func provider(_ provider: CXProvider, perform action: CXStartCallAction) {
    //
    // ...
    //
    // Trigger the call to be started via the underlying network service.
    call.startSpeakerboxCall { success in
        if success {
            // Signal to the system that the action was successfully performed.
            action.fulfill()

            // ...
        } else {
            // Signal to the system that the action was unable to be performed.
            action.fail()
        }
    }
}
```

---

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