Struggling with Twilio Voice Call Integration in Flutter? twilio_voice_flutter Solves It!

Introduction

The twilio_voice_flutter plugin simplifies integration with Twilio’s Programmable Voice SDK, enabling VoIP calling within your Flutter apps. It supports both iOS and Android, offering an easy-to-use API for managing calls. Ideal for customer service, communication, or any app needing real-time voice, it leverages Twilio’s reliable infrastructure to deliver high-quality VoIP features.

Getting Started

Add the dependency to your pubspec.yaml file and run pub get:

dependencies:
  twilio_voice_flutter: ^0.0.3

Then import the package into your Dart file:

import 'package:twilio_voice_flutter/twilio_voice_flutter.dart';

⚠️ Important Note

This plugin requires Firebase setup for Twilio voice calls. It uses FCM tokens for handling calls on Android 📲 and VoIP notifications for iOS 📞. Ensure both platforms are properly configured for smooth call functionality.

Platform Setup

Android

Open your AndroidManifest.xml file and add the following service declaration inside the tag:

    ...
    
        
            
        
    
    ...

iOS

Open Xcode, go to Signing & Capabilities, and enable the following Background Modes: Audio, AirPlay, and Picture in Picture and Voice over IP. Then add the required keys to your Info.plist:

UIBackgroundModes

    audio
    voip

🔑 Twilio Voice Call Access Token Setup

To generate the access token and enable Twilio calls, follow the steps in the official Twilio repositories:

• Twilio Voice Quickstart — Android
• Twilio Voice Quickstart — iOS

Setting Up Twilio Token

The setTwilioToken function registers a user’s identity with Twilio Voice using the provided access token. On Android it also retrieves the FCM token from Firebase Cloud Messaging:

static Future setTwilioToken(String identity, String accessToken) async {
  try {
    String accessToken = await _getAccessToken(identity);
    if (Platform.isAndroid) {
      String? fcmToken = await FirebaseMessaging.instance.getToken() ?? "";
      await TwilioVoiceFlutter.register(
          identity: identity, accessToken: accessToken, fcmToken: fcmToken);
    } else {
      await TwilioVoiceFlutter.register(
          identity: identity, accessToken: accessToken, fcmToken: "");
    }
    return true;
  } catch (_) {
    return false;
  }
}

🔗 Visit the example project for more information

Features

1. VoIP Call Management

• Initiate Calls : Start a VoIP call to any recipient using the makeCall method with custom call data support.
• Receive Incoming Calls : Handle incoming call invites via push notifications with built-in CallKit support on iOS.
• Call Status Notifications : Stay updated on ringing, connecting, and disconnecting states via Flutter MethodChannel callbacks.

2. In-Call Controls

• Mute/Unmute : Toggle mute with toggleMute and check current status with isMuted.
• Speakerphone Control : Switch between speaker and receiver with toggleSpeaker, verify route with isSpeaker.

3. CallKit Integration for iOS

• Native CallKit Support : Manages incoming and outgoing VoIP calls with a familiar native UI experience.
• Background VoIP Support : Receive VoIP calls while the app is in the background via proper background mode configuration.

4. Push Notification Support

• VoIP Push Notifications : Handle VoIP push via FCM on Android and APNs on iOS.
• Push Credential Management : Manage device and access tokens for reliable VoIP push delivery.

5. DTMF Signaling

• Send DTMF Digits : During an active call, send tones using the sendDigits method ideal for automated phone systems.

6. Contact & Data Management

• Custom Contact Data : Store and retrieve display names and photo URLs to personalize the calling experience.
• Persistent Token Storage : Securely store access tokens using UserDefaults on iOS to maintain state across sessions.
• Graceful Error Handling : Token expiration and failed connections are managed and reported to the user effectively.

Function Overview

• registerTwilio() : Registers the device with Twilio using the access token and device token for VoIP push notifications.
• unregisterTwilio() : Unregisters the device from Twilio VoIP push notifications.
• makeCall(String to) : Initiates a voice call to the specified recipient. Returns an error if an active call already exists.
• toggleMute() : Toggles the mute status of the ongoing call and notifies the Flutter side.
• isMuted() : Returns the current mute status of the ongoing call.
• toggleSpeaker() : Toggles speaker mode during an ongoing call and notifies the Flutter side.
• isSpeaker() : Checks if speaker mode is currently active.
• hangUp() : Ends the current call and clears call-related data.
• activeCall() : Returns details of the active call if one exists.
• sendDigits(String digits) : Sends DTMF digits during an active call.

Conclusion

The twilio_voice_flutter plugin provides a robust and production-ready foundation for integrating real-time voice communication into Flutter apps. With support for VoIP call management, in-call controls, CallKit integration, push notifications, DTMF signaling, and persistent data storage, it covers everything needed for customer support, in-app calling, and beyond.

For full documentation and the example project, check it out on pub.dev.