callkit

CallKit

Build VoIP calling features that integrate with the native iOS call UI using CallKit and PushKit. Covers incoming/outgoing call flows, VoIP push registration, audio session coordination, and call directory extensions.

Contents

• Setup
• Provider Configuration
• Incoming Call Flow
• Outgoing Call Flow
• PushKit VoIP Registration
• Audio Session Coordination
• Call Directory Extension and Manager
• Common Mistakes
• Review Checklist
• References

Setup

Project Configuration

1. Enable the Voice over IP background mode in Signing & Capabilities
2. Add the Push Notifications capability
3. For call directory extensions, add a Call Directory Extension target

Key Types

Type	Role
CXProvider	Reports calls to the system, receives call actions
CXCallController	Requests call actions (start, end, hold, mute)
CXCallUpdate	Describes call metadata (caller name, video, handle)
CXProviderDelegate	Handles system call actions and audio session events
PKPushRegistry	Registers for and receives VoIP push notifications
PKVoIPPushMetadata	iOS 26.4+ metadata that says whether a VoIP push must be reported

Provider Configuration

Create a single CXProvider at app launch and keep it alive for the app lifetime. Configure it with a CXProviderConfiguration that describes your calling capabilities.

import CallKit

/// CXProvider dispatches all delegate calls to the queue passed to `setDelegate(_:queue:)`.
/// The `let` properties are initialized once and never mutated, making this type
/// safe to share across concurrency domains despite @unchecked Sendable.
final class CallManager: NSObject, @unchecked Sendable {
    static let shared = CallManager()

    let provider: CXProvider
    let callController = CXCallController()

    private override init() {
        let config = CXProviderConfiguration()
        config.localizedName = "My VoIP App"
        config.supportsVideo = true
        config.maximumCallsPerCallGroup = 1
        config.maximumCallGroups = 2
        config.supportedHandleTypes = [.phoneNumber, .emailAddress]
        config.includesCallsInRecents = true

        provider = CXProvider(configuration: config)
        super.init()
        provider.setDelegate(self, queue: nil)
    }
}

Incoming Call Flow

When a required VoIP call push arrives, report the incoming call to CallKit immediately. The system displays the native call UI. You must report required calls before the PushKit completion handler returns -- failure to do so causes the system to terminate your app.

func reportIncomingCall(
    uuid: UUID,
    handle: String,
    hasVideo: Bool
) async throws {
    let update = CXCallUpdate()
    update.remoteHandle = CXHandle(type: .phoneNumber, value: handle)
    update.hasVideo = hasVideo
    update.localizedCallerName = "Jane Doe"

    try await withCheckedThrowingContinuation {
        (continuation: CheckedContinuation<Void, Error>) in
        provider.reportNewIncomingCall(
            with: uuid,
            update: update
        ) { error in
            if let error {
                continuation.resume(throwing: error)
            } else {
                continuation.resume()
            }
        }
    }
}

Handling the Answer Action

Implement CXProviderDelegate to respond when the user answers:

extension CallManager: CXProviderDelegate {
    func providerDidReset(_ provider: CXProvider) {
        // End all calls, reset audio
    }

    func provider(_ provider: CXProvider, perform action: CXAnswerCallAction) {
        // Prepare audio, then fulfill only after the call is actually ready
        configureAudioSession()
        connectToCallServer(callUUID: action.callUUID) { success in
            if success {
                action.fulfill()
            } else {
                provider.reportCall(
                    with: action.callUUID,
                    endedAt: Date(),
                    reason: .failed
                )
                action.fail()
            }
        }
    }

    func provider(_ provider: CXProvider, perform action: CXEndCallAction) {
        disconnectFromCallServer(callUUID: action.callUUID)
        action.fulfill()
    }
}

Outgoing Call Flow

Use CXCallController to request an outgoing call. The system routes the request through your CXProviderDelegate.

func startOutgoingCall(handle: String, hasVideo: Bool) {
    let uuid = UUID()
    let handle = CXHandle(type: .phoneNumber, value: handle)
    let startAction = CXStartCallAction(call: uuid, handle: handle)
    startAction.isVideo = hasVideo

    let transaction = CXTransaction(action: startAction)
    callController.request(transaction) { error in
        if let error {
            print("Failed to start call: \(error)")
        }
    }
}

Delegate Methods for Outgoing Calls

extension CallManager {
    func provider(_ provider: CXProvider, perform action: CXStartCallAction) {
        configureAudioSession()
        // Begin connecting to server
        provider.reportOutgoingCall(
            with: action.callUUID,
            startedConnectingAt: Date()
        )

        connectToServer(callUUID: action.callUUID) {
            provider.reportOutgoingCall(
                with: action.callUUID,
                connectedAt: Date()
            )
        }
        action.fulfill()
    }
}

PushKit VoIP Registration

Register for VoIP pushes at every app launch and send token changes to your server. For iOS 13 SDK+ apps, every report-required VoIP call push must be reported before PushKit completion using CallKit, or LiveCommunicationKit for apps built on that framework. On iOS 26.4+, PKVoIPPushMetadata.mustReport is the gate: true means report before completion; false means no CallKit or LiveCommunicationKit report is required. Missing a required report before completion can terminate the app, and repeated failures may stop VoIP delivery.

Path	Report decision	Completion timing
iOS 26.4+ mustReport == true	Report with CallKit or LiveCommunicationKit	After report callback
iOS 26.4+ mustReport == false	No CallKit/LiveCommunicationKit report required	After local handling
Older delegate	iOS 13 SDK+ treats VoIP call pushes as report-required	After report callback

import PushKit

final class PushManager: NSObject, PKPushRegistryDelegate {
    let registry: PKPushRegistry

    override init() {
        registry = PKPushRegistry(queue: .main)
        super.init()
        registry.delegate = self
        registry.desiredPushTypes = [.voIP]
    }

    func pushRegistry(
        _ registry: PKPushRegistry,
        didUpdate pushCredentials: PKPushCredentials,
        for type: PKPushType
    ) {
        let token = pushCredentials.token
            .map { String(format: "%02x", $0) }
            .joined()
        // Send token to your server
        sendTokenToServer(token)
    }

    @available(iOS 26.4, *)
    func pushRegistry(
        _ registry: PKPushRegistry,
        didReceiveIncomingVoIPPushWith payload: PKPushPayload,
        metadata: PKVoIPPushMetadata,
        withCompletionHandler completion: @escaping @Sendable () -> Void
    ) {
        guard metadata.mustReport else {
            completion()
            return
        }
        handleIncomingVoIPPush(payload, completion: completion)
    }

    // Keep the older callback for iOS 26.0-26.3 and older deployment targets.
    func pushRegistry(
        _ registry: PKPushRegistry,
        didReceiveIncomingPushWith payload: PKPushPayload,
        for type: PKPushType,
        completion: @escaping () -> Void
    ) {
        guard type == .voIP else {
            completion()
            return
        }

        handleIncomingVoIPPush(payload, completion: completion)
    }

    private func handleIncomingVoIPPush(
        _ payload: PKPushPayload,
        completion: @escaping () -> Void
    ) {
        let callUUID = UUID()
        let handle = payload.dictionaryPayload["handle"] as? String ?? "Unknown"

        Task {
            do {
                try await CallManager.shared.reportIncomingCall(
                    uuid: callUUID,
                    handle: handle,
                    hasVideo: false
                )
            } catch {
                // Call was filtered by DND or block list
            }
            completion()
        }
    }
}

Server-side VoIP pushes should use a short lifetime: set apns-expiration to 0 or only a few seconds. After the initial push wakes the app, send hangups and call-detail changes over the app-server connection instead of sending more VoIP pushes.

Audio Session Coordination

CallKit owns the audio activation boundary: start media only in provider(_:didActivate:), and stop or tear it down in provider(_:didDeactivate:) and reset paths.

extension CallManager {
    func provider(_ provider: CXProvider, didActivate audioSession: AVAudioSession) {
        // Audio session is now active -- start audio engine / WebRTC
        startAudioEngine()
    }

    func provider(_ provider: CXProvider, didDeactivate audioSession: AVAudioSession) {
        // Audio session deactivated -- stop audio engine
        stopAudioEngine()
    }

    func configureAudioSession() {
        let session = AVAudioSession.sharedInstance()
        do {
            try session.setCategory(
                .playAndRecord,
                mode: .voiceChat,
                options: [.allowBluetooth, .allowBluetoothA2DP]
            )
        } catch {
            print("Audio session configuration failed: \(error)")
        }
    }
}

Call Directory Extension and Manager

Use Call Directory for preloaded caller ID/blocking, not per-call API lookup. The extension loads sorted bulk data in beginRequest(with:); the main app uses CXCallDirectoryManager to check enabled status, open Call Blocking & Identification settings when disabled, and reload after data changes. Store CXCallDirectoryPhoneNumber as country code plus digits in ascending order (for example 18005551234), not a formatted string.

import CallKit

final class CallDirectoryHandler: CXCallDirectoryProvider {
    override func beginRequest(
        with context: CXCallDirectoryExtensionContext
    ) {
        if context.isIncremental {
            addOrRemoveIncrementalEntries(to: context)
        } else {
            addAllEntries(to: context)
        }
        context.completeRequest()
    }

    private func addAllEntries(
        to context: CXCallDirectoryExtensionContext
    ) {
        // Country code + digits, sorted in ascending order
        let blockedNumbers: [CXCallDirectoryPhoneNumber] = [
            18005551234, 18005555678
        ]
        for number in blockedNumbers {
            context.addBlockingEntry(
                withNextSequentialPhoneNumber: number
            )
        }

        let identifiedNumbers: [(CXCallDirectoryPhoneNumber, String)] = [
            (18005551111, "Local Pizza"),
            (18005552222, "Dentist Office")
        ]
        for (number, label) in identifiedNumbers {
            context.addIdentificationEntry(
                withNextSequentialPhoneNumber: number,
                label: label
            )
        }
    }
}

Main-App Manager: Status, Settings, Reload

let manager = CXCallDirectoryManager.sharedInstance
manager.getEnabledStatusForExtension(withIdentifier: extensionID) { status, _ in
    guard status == .enabled else {
        manager.openSettings { _ in } // Call Blocking & Identification
        return
    }
    manager.reloadExtension(withIdentifier: extensionID) { _ in }
}

Check getEnabledStatusForExtension(...) before assuming the extension is active, use openSettings(...) for Call Blocking & Identification when disabled, and call reloadExtension(...) after data changes. Route APNs auth-key rotation and normal remote-notification setup to push-notifications.

Common Mistakes

Mistake	Fix
Required VoIP push is treated as data-only	Apply the version-specific report rule, report before completion, then invoke the PushKit completion handler.
Answer action is fulfilled before media/server readiness	Keep it pending while connecting; fulfill on readiness or fail and report .failed.
Media starts before provider(_:didActivate:)	Prepare earlier if needed, but start only after activation and stop on deactivation/reset.
An action path never calls fulfill() or fail()	Give success, cancellation, timeout, and network-error paths one terminal action.
Token refresh is ignored	Send every didUpdate pushCredentials token to the server.
Call Directory performs per-call networking	Preload sorted entries and reload the extension.

Review Checklist

• VoIP background mode enabled in capabilities
• Single CXProvider instance created at app launch and retained
• CXProviderDelegate set before reporting any calls
• iOS 26.4+ PushKit path reports when mustReport is true and may skip when false
• iOS 13 SDK+ PushKit VoIP call pushes report to CallKit before completion
• VoIP APNs requests use apns-expiration of 0 or only a few seconds
• Hangups and detail updates use the app-server connection after the initial push
• action.fulfill() or action.fail() called for every provider delegate action
• CXAnswerCallAction fulfilled only after the call server/media connection is ready
• Audio engine started only after provider(_:didActivate:) callback
• Audio engine stopped in provider(_:didDeactivate:) callback
• Audio session category set to .playAndRecord with .voiceChat mode
• VoIP push token sent to server on every didUpdate pushCredentials callback
• PKPushRegistry created at every app launch (not lazily)
• Call Directory data is preloaded, not fetched per incoming call
• CXCallDirectoryPhoneNumber documented as country calling code + digits
• CXCallDirectoryManager names status check, reload, and settings-opening APIs
• CXCallUpdate populated with localizedCallerName and remoteHandle
• Outgoing calls report startedConnectingAt and connectedAt timestamps
• iOS 26 call translation keeps upstream audio active during mute
• Encrypted metadata filtering mentions the notification service extension entitlement

References

• Extended patterns (hold, mute, group calls, delegate lifecycle): references/callkit-patterns.md
• CallKit framework
• CXProvider
• CXCallController
• CXCallAction
• CXCallUpdate
• CXProviderConfiguration
• CXProviderDelegate
• PKPushRegistry
• PKPushRegistryDelegate
• PKVoIPPushMetadata
• CXCallDirectoryProvider
• CXCallDirectoryPhoneNumber
• CXCallDirectoryManager
• CXSetTranslatingCallAction
• reportNewIncomingVoIPPushPayload(_:completion:)
• Making and receiving VoIP calls
• Responding to VoIP Notifications from PushKit