Definition

Starting an outgoing call in CallKit means requesting the iOS telephony system to begin a call that was initiated by the user inside your app.

This is done using:

CXStartCallAction

wrapped inside:

CXTransaction

and sent through:

CXCallController

Core Concept

Outgoing calls are app-initiated actions.

The app does not directly start the call.

Instead, it asks the system:

“The user wants to start this call. Can CallKit coordinate it?”

Basic Flow

User taps call button
        ↓
App creates UUID
        ↓
App creates CXHandle
        ↓
App creates CXStartCallAction
        ↓
App wraps action in CXTransaction
        ↓
CXCallController sends request
        ↓
System validates request
        ↓
CXProviderDelegate confirms start

Code Example

func startOutgoingCall(to recipient: String) {
    let uuid = UUID()

    let handle = CXHandle(
        type: .phoneNumber,
        value: recipient
    )

    let startAction = CXStartCallAction(
        call: uuid,
        handle: handle
    )

    startAction.isVideo = false

    let transaction = CXTransaction(action: startAction)

    callController.request(transaction) { error in
        if let error = error {
            print("Failed to start call:", error.localizedDescription)
        } else {
            print("Outgoing call request sent")
        }
    }
}