Firetell Flutter WebRTC SDK

A Flutter SDK for building VoIP-enabled mobile applications with the Firetell platform. Supports audio and video calls, camera controls (switch camera, mute/unmute video), hold, mute, DTMF, call transfer, and VoIP push notifications (FCM & APNs) with native WebSocket event-based signaling.

Features

• Authentication — Workspace domain + JWT-based authentication
• Outbound Calls — Initiate audio and video calls via REST API + WebRTC
• Video Calls — Full video calling with local Picture-in-Picture preview, remote video rendering, camera switching (front/back), and video mute/unmute
• Phone Numbers (DIDs) — Query agent/team accessible numbers to use as outbound Caller ID
• Incoming Calls — Accept/reject via WebSocket or VoIP push notifications (auto-detects audio vs video)
• Call Controls — Mute, speakerphone (loudspeaker/earpiece), camera toggle, switch camera, hold/unhold, DTMF, transfer
• VoIP Push — FCM (Android) and APNs VoIP (iOS) push notification support
• Full ICE — Complete ICE candidate gathering before SDP exchange
• Real-time Events — SSE stream for workspace events (agent state, call ring, etc.)

Installation

Requirements

Component	Minimum
Flutter	3.38.1
Dart	3.10.0
iOS	15.0
Android	API 24 with compileSdk 36 and targetSdk 36

Warning

VERSION REQUIREMENTS: Do not rely on the lower Flutter, Dart or iOS values currently declared in pubspec.yaml. The resolved native dependencies require Flutter 3.38.1 or newer, Dart 3.10.0 or newer, iOS 15.0 or newer, and Android compileSdk/targetSdk 36. An iOS target below 15 fails during pod installation.

Add to your pubspec.yaml:

dependencies:
  firetell_flutter_sdk: ^1.1.1

See INSTALLATION.MD for complete Android/iOS setup, CallKit UUID requirements and the production validation checklist.

Quick Start

1. Initialize the Client

import 'package:firetell_flutter_sdk/firetell_flutter_sdk.dart';

final client = FiretellClient(
  jwt: 'your_agent_or_client_jwt_token',
  domain: 'your_workspace.firetell.app',
);

// Wait for initialization
final session = await client.ready;
print('Connected as ${session.username}');

2. Make an Outbound Call

// Fetch accessible phone numbers (DIDs) for Caller ID
final phoneNumbers = await client.getPhoneNumbers();
final callerId = phoneNumbers.firstOrNull?.number; // e.g. '+14155552671'

final call = await client.makeOutboundCall(
  to: '+1234567890',
  from: callerId, // Outbound Caller ID (required for PSTN/mobile calls)
);

// Listen for call state changes
call.onStateChange.listen((event) {
  print('Call state: ${event.state}');
  if (event.state == CallState.active) {
    print('Call connected!');
  }
});

// Hang up
await call.hangup();

3. Handle Incoming Calls (SSE — Foreground)

client.onCallRing.listen((params) async {
  print('Incoming call from ${params.callerName} (${params.callerNumber})');

  final call = await client.handlePushIncomingCall(params);

  // Call this after the user taps "Answer" in your incoming-call UI.
  await call.accept();
});

4. Handle Incoming Calls (VoIP Push — Background)

// Parse the push payload
final ringParams = CallRingParams.fromFcmData(pushData);

// Show native incoming call UI via flutter_callkit_incoming
// ...

// When user answers:
final call = await client.handlePushIncomingCall(ringParams);
await call.accept();

// When user declines (fast HTTP reject, no WS needed):
final tempCall = Call(iceServers: client.iceServers);
tempCall.callId = ringParams.callId;
await tempCall.rejectViaHttp(
  baseUrl: client.baseUrl,
  callToken: ringParams.callToken,
);

5. Register Push Tokens

// Register VoIP push token (on every cold launch / token refresh)
await PushTokenService.registerVoipPushToken(
  baseUrl: client.baseUrl,
  jwt: client.jwt,
  pushToken: fcmToken, // or APNs VoIP token
  deviceId: await DeviceIdHelper.getOrCreate(),
  platform: 'android', // or 'ios'
);

// Register notification token (for call.canceled / call.ended dismissal)
await PushTokenService.registerNotificationPushToken(
  baseUrl: client.baseUrl,
  jwt: client.jwt,
  notificationToken: fcmToken,
  deviceId: await DeviceIdHelper.getOrCreate(),
  platform: 'android',
);

Call Controls

// Mute / Unmute
await call.mute();
await call.unmute();
await call.toggleMute();

// Speakerphone (Loudspeaker / Earpiece)
await call.setSpeakerphoneOn(true);  // Turn on loudspeaker
await call.setSpeakerphoneOn(false); // Route back to earpiece
await call.toggleSpeaker();
print('Speaker active: ${call.isSpeakerOn}');

// Video & Camera Controls
await call.switchCamera();           // Switch front / back camera
await call.muteVideo();              // Turn off camera
await call.unmuteVideo();            // Turn on camera
await call.toggleCamera();           // Toggle camera on/off
print('Camera off: ${call.isCameraOff}');

// Hold / Unhold
await call.onhold();
await call.unhold();

// DTMF
call.sendDTMF('1');
call.sendDTMF('#');

// Transfer
await call.transfer('+1987654321', reason: 'Customer request');

// Hang up
await call.hangup();

Call State Machine

Outbound: none → initiated → ringing → answered → active → ended
Inbound:  none → ringing → answered → active → ended
Hold:     active ↔ onHold

WebSocket Signaling Protocol

The SDK uses the same native WebSocket event-based JSON signaling protocol as the Firetell browser SDK:

Event	Direction	Description
session.connect	Client → Server	Authenticate with call_token (must be within 3s)
session.connected	Server → Client	Authentication ACK
call.offer	Client → Server	SDP Offer (audio / video)
call.answer	Client → Server	SDP Answer
call.hold	Client → Server	Hold call (with renegotiated SDP)
call.unhold	Client → Server	Unhold call (with renegotiated SDP)
call.hangup	Client → Server	End call
call.reject	Client → Server	Reject incoming call
call.mute	Client → Server	Mute/unmute microphone notification
call.camera	Client ⇄ Server	Camera state change notification (muted: true/false)
call.dtmf	Client → Server	DTMF digit
call.transfer	Client → Server	Transfer call

Architecture

FiretellClient
├── REST API (POST /api/v1/call-center/calls → call_id, call_token, ws_url)
├── SSE Stream (GET /stream → real-time workspace events)
└── Call (per-call instance)
    ├── Native WebSocket (ws_url, authenticated via call_token)
    └── RTCPeerConnection (flutter_webrtc, Full ICE)

Platform Setup

Android

Add to AndroidManifest.xml:

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />

<!-- Bluetooth headset audio routing (Required for Android 12+) -->
<uses-permission android:name="android.permission.BLUETOOTH" android:maxSdkVersion="30" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" android:maxSdkVersion="30" />
<uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />

iOS

Add to Info.plist:

<key>NSMicrophoneUsageDescription</key>
<string>Firetell needs microphone access for VoIP calls</string>
<key>NSCameraUsageDescription</key>
<string>Firetell needs camera access for video calls</string>
<key>UIBackgroundModes</key>
<array>
  <string>voip</string>
  <string>audio</string>
  <string>fetch</string>
  <string>remote-notification</string>
</array>

License

MIT — see LICENSE for details.