JSPM

Capacitor Twilio Voice Plugin

A Capacitor plugin for integrating Twilio Voice calling functionality into iOS and Android applications.

Installation

npm install @capgo/capacitor-twilio-voice
npx cap sync

iOS Setup

1. Install the plugin

npm install @capgo/capacitor-twilio-voice
npx cap sync

2. Setup CustomCapacitorViewController.swift

Copy the code from example-app/ios/App/App/CustomCapacitorViewController.swift to your ios/App/App/CustomCapacitorViewController.swift file.

3. Modify AppDelegate.swift

Add the following to AppDelegate.swift:

import UIKit
import Capacitor
+ import PushKit
+ import CapgoCapacitorTwilioVoice

@UIApplicationMain
- class AppDelegate: UIResponder, UIApplicationDelegate {
+ class AppDelegate: UIResponder, UIApplicationDelegate, PKPushRegistryDelegate {

    var window: UIWindow?
+     var pushKitEventDelegate: PushKitEventDelegate?
+     var voipRegistry = PKPushRegistry.init(queue: DispatchQueue.main)

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
+         
+         /*
+          * Your app must initialize PKPushRegistry with PushKit push type VoIP at the launch time. As mentioned in the
+          * [PushKit guidelines](https://developer.apple.com/documentation/pushkit/supporting_pushkit_notifications_in_your_app),
+          * the system can't deliver push notifications to your app until you create a PKPushRegistry object for
+          * VoIP push type and set the delegate. If your app delays the initialization of PKPushRegistry, your app may receive outdated
+          * PushKit push notifications, and if your app decides not to report the received outdated push notifications to CallKit, iOS may
+          * terminate your app.
+          */
+         initializePushKit()
+         
+         guard let viewController = UIApplication.shared.windows.first?.rootViewController as? CustomCapacitorViewController else {
+             fatalError("Root view controlelr is not Capacitor view controller")
+         }
+         
+         viewController.passPushKitEventDelegate = { delegate in
+             self.pushKitEventDelegate = delegate
+         }
+         
+         // self.pushKitEventDelegate = viewController
+         
        return true
    }
+     
+     func initializePushKit() {
+         voipRegistry.delegate = self
+         voipRegistry.desiredPushTypes = Set([PKPushType.voIP])
+     }

    // ... (existing lifecycle methods remain the same) ...

+     // MARK: PKPushRegistryDelegate
+     func pushRegistry(_ registry: PKPushRegistry, didUpdate credentials: PKPushCredentials, for type: PKPushType) {
+         NSLog("pushRegistry:didUpdatePushCredentials:forType:")
+         
+         if let delegate = self.pushKitEventDelegate {
+             delegate.credentialsUpdated(credentials: credentials)
+         }
+     }
+     
+     func pushRegistry(_ registry: PKPushRegistry, didInvalidatePushTokenFor type: PKPushType) {
+         NSLog("pushRegistry:didInvalidatePushTokenForType:")
+         
+         if let delegate = self.pushKitEventDelegate {
+             delegate.credentialsInvalidated()
+         }
+     }
+ 
+     /**
+      * Try using the `pushRegistry:didReceiveIncomingPushWithPayload:forType:withCompletionHandler:` method if
+      * your application is targeting iOS 11. According to the docs, this delegate method is deprecated by Apple.
+      */
+     func pushRegistry(_ registry: PKPushRegistry, didReceiveIncomingPushWith payload: PKPushPayload, for type: PKPushType) {
+         NSLog("pushRegistry:didReceiveIncomingPushWithPayload:forType:")
+         
+         if let delegate = self.pushKitEventDelegate {
+             delegate.incomingPushReceived(payload: payload)
+         }
+     }
+ 
+     /**
+      * This delegate method is available on iOS 11 and above. Call the completion handler once the
+      * notification payload is passed to the `TwilioVoiceSDK.handleNotification()` method.
+      */
+     func pushRegistry(_ registry: PKPushRegistry, didReceiveIncomingPushWith payload: PKPushPayload, for type: PKPushType, completion: @escaping () -> Void) {
+         NSLog("pushRegistry:didReceiveIncomingPushWithPayload:forType:completion:")
+ 
+         if let delegate = self.pushKitEventDelegate {
+             delegate.incomingPushReceived(payload: payload, completion: completion)
+         }
+         
+         if let version = Float(UIDevice.current.systemVersion), version >= 13.0 {
+             /**
+              * The Voice SDK processes the call notification and returns the call invite synchronously. Report the incoming call to
+              * CallKit and fulfill the completion before exiting this callback method.
+              */
+             completion()
+         }
+     }

}

3. Edit Main.storyboard

Change the view controller to CustomCapacitorViewController in Main.storyboard.

<?xml version="1.0" encoding="UTF-8"?>
<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="14111" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" colorMatched="YES" initialViewController="BYZ-38-t0r">
    <device id="retina4_7" orientation="portrait">
        <adaptation id="fullscreen"/>
    </device>
    <dependencies>
        <deployment identifier="iOS"/>
        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="14088"/>
    </dependencies>
    <scenes>
        <!--Bridge View Controller-->
        <scene sceneID="tne-QT-ifu">
            <objects>
-                <viewController id="BYZ-38-t0r" customClass="CAPBridgeViewController" customModule="Capacitor" sceneMemberID="viewController"/>
+                <viewController id="BYZ-38-t0r" customClass="CustomCapacitorViewController" customModule="App" customModuleProvider="target" sceneMemberID="viewController"/>
                <placeholder placeholderIdentifier="IBFirstResponder" id="dkx-z0-nzr" sceneMemberID="firstResponder"/>
            </objects>
        </scene>
    </scenes>
</document>

Look in the example app for more details.

4. Setup Info.plist

Add the following to ios/App/App/Info.plist:

<key>NSMicrophoneUsageDescription</key>
<string>This app uses the microphone for voice calls</string>

<key>UIBackgroundModes</key>
<array>
    <string>voip</string>
    <string>audio</string>
</array>

5. Make sure you have the following capabilities enabled in Xcode:

• Push Notifications
• Background Modes

6. Generate the certificate for Push Notifications

In order to generate the certificate for Push Notifications, you need to follow these steps:

1. Generate the signing certificate for your app.

openssl genrsa -out ALDsigning.key 2048

2. Generate the signing request.

openssl req -new -key ALDsigning.key -out csr3072ALDSigning.certSigningRequest -subj "/emailAddress=example@example.com, CN=Example Name, C=IE"

Then, please upload it to your Apple Developer account here. Search for Create a new VoIP Services Certificate

3. Download the file provided by Apple.

4. Extract the .p12 file from the downloaded file.

openssl pkcs12 -export -out voip_services.p12 -inkey ALDsigning.key -in voip_services.cer

5. Export the cert.pem and key.pem files from the .p12 file.

openssl pkcs12 -in voip_services.p12 -nokeys -out cert.pem -nodes
openssl pkcs12 -in voip_services.p12 -nocerts -out key.pem -nodes

6. Upload the cert.pem and key.pem files twilio.

npx twilio api:chat:v2:credentials:create --type=apn --sandbox --friendly-name="voice-push-credential (sandbox)" --certificate="$(cat /Users/your_username/Documents/twilio-voip/cert.pem)" --private-key="$(cat /Users/your_username/Documents/twilio-voip/key.pem)"

Android Setup

1. Firebase Setup

Add Firebase to your Android project:

1. Add google-services.json to android/app/

2. Add CapacitorApplication.java to android/app/src/main/java/YOUR_APP_PACKAGE/CapacitorApplication.java Copy the content of example-app/android/app/src/main/java/com/example/plugin/CapacitorApplication.java to your android/app/src/main/java/YOUR_APP_PACKAGE/CapacitorApplication.java file.

3. Import androidx.webkit:webkit in build.gradle (module :app)

dependencies {
+     implementation 'androidx.webkit:$androidxWebkitVersion'
}

4. Modify MainActivity.java

Add the following to MainActivity.java:

package com.example.plugin;

import android.net.Uri;
import android.os.Bundle;
import android.webkit.ValueCallback;

import androidx.webkit.WebViewCompat;
import androidx.webkit.WebViewFeature;

import com.getcapacitor.BridgeActivity;
import com.getcapacitor.JSExport;
import com.getcapacitor.Logger;
import com.getcapacitor.PluginHandle;

+ import java.util.ArrayList;
+ import java.util.Collections;

import ee.forgr.capacitor_twilio_voice.CapacitorTwilioVoicePlugin;

public class MainActivity extends BridgeActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
+         
+         this.bridge.registerPluginInstance(CapacitorTwilioVoicePlugin.getInstance());
+         ArrayList<PluginHandle> pluginHandles = new ArrayList<>();
+         pluginHandles.add(this.bridge.getPlugin("CapacitorTwilioVoice"));
+         String pluginJS = JSExport.getPluginJS(pluginHandles);
+         if (WebViewFeature.isFeatureSupported(WebViewFeature.DOCUMENT_START_SCRIPT)) {
+             String allowedOrigin = Uri.parse(this.bridge.getAppUrl()).buildUpon().path(null).fragment(null).clearQuery().build().toString();
+             try {
+                 WebViewCompat.addDocumentStartJavaScript(this.getBridge().getWebView(), pluginJS, Collections.singleton(allowedOrigin));
+             } catch (IllegalArgumentException ex) {
+                 Logger.warn("Invalid url, using fallback");
+             }
+         }
    }
}

5. Register the plugin in JS

+ import { CapacitorTwilioVoice } from '@capgo/capacitor-twilio-voice';
+ import { Capacitor } from '@capacitor/core';

+ Capacitor.registerPlugin('CapacitorTwilioVoice');

6. Add android:name="CapacitorApplication" to the application tag in android/app/src/main/AndroidManifest.xml

7. Add the following to android/app/src/main/AndroidManifest.xml:

    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.TURN_SCREEN_ON" />
    <uses-permission android:name="android.permission.SHOW_WHEN_LOCKED" />

Keep in mind, this will make it so that you app can be accessed when the screen is locked.

Twilio Setup

• iOS Setup
• Android Setup

Usage

Authentication

login(options: { accessToken: string })

Authenticates with Twilio using a JWT access token:

• Validates token expiration automatically
• Stores token securely for app restarts
• Registers for VoIP push notifications
• Note: The plugin will reject expired tokens

logout()

Logs out the current user and cleans up all session data:

• Unregisters from VoIP push notifications
• Clears stored access tokens
• Ends any active calls
• Resets all call state

isLoggedIn()

Checks if user is currently logged in with a valid (non-expired) token. Returns: { isLoggedIn: boolean, hasValidToken: boolean, identity?: string }

The identity field contains the user identity extracted from the JWT token if logged in.

makeCall(options: { to: string })

Initiates an outgoing call. Requires prior authentication via login().

acceptCall(options: { callSid: string })

Accepts an incoming call.

rejectCall(options: { callSid: string })

Rejects an incoming call.

endCall(options?: { callSid?: string })

Ends the active call or a specific call.

muteCall(options: { muted: boolean, callSid?: string })

Mutes or unmutes the microphone.

setSpeaker(options: { enabled: boolean })

Enables or disables the speaker. On Android, uses Twilio AudioSwitch to manage audio routing between earpiece, speaker, and connected devices (headsets, Bluetooth, etc.).

getCallStatus()

Gets the current call status.

checkMicrophonePermission()

Checks if microphone permission is granted.

requestMicrophonePermission()

Requests microphone permission from the user.

Event Listeners

import { CapacitorTwilioVoice } from '@capgo/capacitor-twilio-voice';

// Registration events
CapacitorTwilioVoice.addListener('registrationSuccess', (data) => {
  console.log('Successfully registered:', data);
});

CapacitorTwilioVoice.addListener('registrationFailure', (data) => {
  console.error('Registration failed:', data);
});

// Call events
CapacitorTwilioVoice.addListener('callInviteReceived', (data) => {
  console.log('Incoming call from:', data.from);
});

CapacitorTwilioVoice.addListener('callConnected', (data) => {
  console.log('Call connected:', data);
});

CapacitorTwilioVoice.addListener('callDisconnected', (data) => {
  console.log('Call ended:', data);
});

CapacitorTwilioVoice.addListener('callRinging', (data) => {
  console.log('Call is ringing:', data);
});

CapacitorTwilioVoice.addListener('callReconnecting', (data) => {
  console.log('Call reconnecting:', data);
});

CapacitorTwilioVoice.addListener('callReconnected', (data) => {
  console.log('Call reconnected:', data);
});

CapacitorTwilioVoice.addListener('callQualityWarningsChanged', (data) => {
  console.log('Quality warnings:', data);
});

JWT Token Management

Token Format

The plugin expects Twilio access tokens in JWT format with this structure:

{
  "iss": "your-account-sid",
  "exp": 1234567890,
  "grants": {
    "voice": {
      "outgoing": {
        "application_sid": "your-app-sid"
      },
      "push_credential_sid": "your-push-credential-sid"
    },
    "identity": "user-identity"
  }
}

Token Validation

• Tokens are automatically validated for expiration
• Invalid or expired tokens will be rejected
• Use isLoggedIn() to check token status

Backend Integration

Fetch access tokens from your backend server:

async function fetchAccessToken(identity: string): Promise<string> {
  const response = await fetch(`/accessToken?identity=${identity}`);
  return response.text();
}

Testing Requirements

iOS Simulator Limitations

• VoIP push notifications don't work in the iOS Simulator
• Use a physical iOS device for testing incoming calls
• Outgoing calls work in both Simulator and device

Android Emulator

• Requires Google Play Services
• Firebase messaging works in Android Emulator with Google APIs

Error Handling

The plugin provides detailed error information:

try {
  await CapacitorTwilioVoice.makeCall({ to: '+1234567890' });
} catch (error) {
  console.error('Call failed:', error);
}

Common error scenarios:

• Invalid token: Check token format and expiration
• No microphone permission: Call requestMicrophonePermission()
• Network issues: Verify internet connectivity
• Invalid phone number: Use E.164 format (+1234567890)

Security Notes

• Access tokens are stored in secure device storage
• Tokens are automatically validated before use
• No sensitive data is logged in production builds
• Always use HTTPS for token fetching from your backend

Platform Support