Hello,
I’m developing a third-party VoIP app called Heyno and trying to support Siri-initiated calls so they behave like WhatsApp / FaceTime, especially from the lock screen.
Target behavior
From the locked device, the user says:
“Hey Siri, call <contact> using Heyno”
Expected result:
• System CallKit audio-call UI appears.
• No “continue in ” sheet, no forced unlock or foregrounding.
• Our app handles the VoIP leg in the background via CXProviderDelegate.
WhatsApp already does this with:
“Hey Siri, call <contact> on WhatsApp”
I’m trying to reproduce that behavior for Heyno using public APIs.
I have followed the SiriKit + CallKit VoIP docs but cannot get a clean Siri → CallKit → app flow from the lock screen without either:
Being forced into .continueInApp (unlock + foreground), or
Hitting CallKit transaction errors when starting the call from the app in response to the intent.
Current implementation
Intents extension (INStartCallIntentHandling)
• resolveContacts(for:with:) normalizes to E.164 and returns INPersonResolutionResult.success.
• resolveDestinationType → .success(.normal).
• resolveCallCapability → .success(.audioCall).
Confirm / handle currently:
func confirm(intent: INStartCallIntent,
completion: @escaping (INStartCallIntentResponse) -> Void) {
completion(INStartCallIntentResponse(code: .ready, userActivity: nil))
}
func handle(intent: INStartCallIntent,
completion: @escaping (INStartCallIntentResponse) -> Void) {
completion(INStartCallIntentResponse(code: .ready, userActivity: nil))
}
Earlier, I used .continueInApp with an NSUserActivity carrying the normalized number and metadata, but that always produced a “Continue in Heyno” sheet that requires unlock and foreground, which breaks the lock-screen Siri flow.
App target – CallKit provider
In the app I have CXProvider + CXProviderDelegate, which work correctly when calls are initiated from inside the app:
func provider(_ provider: CXProvider, perform action: CXStartCallAction) {
let handle = action.handle.value
// Start VoIP / WebRTC / LiveKit / Asterisk call here
provider.reportOutgoingCall(with: action.callUUID,
startedConnectingAt: Date())
provider.reportOutgoingCall(with: action.callUUID,
connectedAt: Date())
action.fulfill()
}
If I construct a CXStartCallAction and submit it via CXCallController.request(...) from the app, CallKit UI appears and our pipeline runs correctly.
What I tried and what fails
Starting CallKit from the Intents extension
Calling CXCallController.request(...) directly from handle(intent:completion:) in the extension always yields:
com.apple.CallKit.error.requesttransaction error 1 (unentitled)
The extension does not have the CallKit entitlement, and the docs say not to initiate calls from the extension, so this path seems unsupported.
Using .continueInApp + NSUserActivity
Pattern:
• handle(intent:) builds NSUserActivity (activityType = NSStringFromClass(INStartCallIntent.self), title = "Heyno Start Call", userInfo with E.164 handle, etc.).
• Returns INStartCallIntentResponse(code: .continueInApp, userActivity: activity).
• App receives the activity, then starts CallKit + VoIP.
Functionally this works, but iOS always requires unlock + foreground (“Continue in Heyno”), which is not acceptable for a Siri lock-screen call.
App group + Darwin notification (extension → app → CallKit)
Experiment:
• Extension writes the normalized number into an app-group UserDefaults.
• Extension posts a Darwin notification.
• App (if running) listens, reads the number, and initiates CXStartCallAction + VoIP.
Observed:
• Works only when the app is already running in the background; a killed app is not woken.
• In some states I see CXErrorCodeRequestTransactionError.invalidAction (error 6) if I try to issue a CXStartCallAction while CallKit is already doing something as part of the Siri flow.
• Siri sometimes replies “There was a problem with the app,” likely because CallKit rejects the transaction or sees duplicate/conflicting actions.
My understanding so far
• The Intents extension should resolve/confirm the intent but not start the call.
• The source of truth for starting a call should be:
Siri → CallKit → app’s CXProviderDelegate.provider(_:perform: CXStartCallAction)
• The app then starts the VoIP leg, reports started/connected, and fulfills.
Where I am stuck
What is not clear is how Siri is supposed to route an INStartCallIntent into CallKit for a third-party VoIP app on a locked device without using .continueInApp.
If my extension simply:
• resolves the contact,
• confirm → .ready,
• handle → .ready (no NSUserActivity, no CallKit),
I do not see a documented mechanism that causes:
“Hey Siri, call <contact> using Heyno”
on the lock screen to:
• Present a CallKit audio call bound to Heyno, and
• Deliver CXStartCallAction to my CXProviderDelegate while the app stays in the background.
Questions
For third-party VoIP apps today, is it recommended to implement INStartCallIntentHandling at all, or should we rely only on CallKit registration and Siri’s built-in support for “Call with ” (no SiriKit extension)?
If an INStartCallIntentHandling extension is still the intended pattern:
• Should confirm/handle simply return .ready and never start CallKit or set NSUserActivity?
• In that case, is Siri expected to invoke CallKit on our behalf and create a CXStartCallAction targeting our provider, even when the device is locked and the app is not foreground?
Is there any supported way for a Siri-triggered third-party VoIP call to start from the lock screen via CallKit without:
• using .continueInApp (unlock + foreground), and
• starting CallKit directly from the Intents extension (unentitled)?
Is there any additional configuration, entitlement, provisioning profile flag, or Info.plist key required so that Siri can map “Call using Heyno” directly to our CallKit provider and background VoIP implementation?
Current options:
• .continueInApp + NSUserActivity → works, but always requires unlock + app UI.
• Start CallKit from the extension → fails with “unentitled” and appears unsupported.
• Extension → app-group + notification → app → CallKit → VoIP → fragile, with intermittent CXErrorCodeRequestTransactionError.invalidAction.
• Remove the extension and hope Siri/CallKit auto-routes to our provider → unclear if this is supported for third-party VoIP apps or reserved for privileged apps.
I would appreciate guidance on the intended architecture for this scenario, and whether the “Siri from lock screen → CallKit UI → background VoIP call” flow is achievable for an App Store VoIP app like Heyno using public APIs only.
