SignalWire Call Widget

A modern JavaScript widget that enables click-to-call functionality using the SignalWire SDK. The widget supports both outgoing and incoming calls, with a customizable UI and multiple window modes.

Installation

NPM

npm install @signalwire/call-widget

CDN (jsDelivr)

<script src="https://cdn.jsdelivr.net/npm/@signalwire/call-widget/dist/c2c-widget-full.umd.min.js"></script>

Quick Start

<button id="myCallButton">Start Call</button>

<call-widget
  button-id="myCallButton"
  token="your_signalwire_token"
  destination="/private/demo"
  support-audio="true"
  support-video="true"
></call-widget>

Dialer Mode

When no destination attribute is provided, the widget automatically displays a dialer UI, allowing users to enter phone numbers or SIP addresses:

<button id="dialerButton">Open Dialer</button>

<call-widget
  button-id="dialerButton"
  token="your_signalwire_token"
  support-audio="true"
></call-widget>

Attributes Reference

Attribute	Required	Default	Description
token	Yes	-	SignalWire authentication token
button-id	Yes	-	ID of the button that triggers the call
destination	No	-	Call destination path (if not provided, dialer opens)
support-audio	No	false	Enable audio support
support-video	No	false	Enable video support
window-mode	No	"video+transcript"	UI mode for the call window
log-level	No	"error"	Logging verbosity level
debug-ws-traffic	No	false	Enable WebSocket traffic debugging
host	No	-	SignalWire server host
receive-calls	No	false	Enable incoming call reception
auto-answer	No	false	Automatically answer incoming calls without prompt
audio-codec	No	-	Comma-separated list of preferred audio codecs
user-variables	No	-	Custom variables passed as JSON string
background-image	No	default	Background image URL for the call interface
background-thumbnail	No	default	Background thumbnail for loading states

Detailed Attribute Description

Required Attributes

token

Your SignalWire authentication token. This is required for establishing connections. You can use C2C tokens, embed tokens, or any Call Fabric authentication token with necessary permissions.

Example:

<call-widget token="your_signalwire_token"></call-widget>

button-id

The ID of the HTML button element that will trigger the call. The widget will wait for the button to be created if it doesn't exist at initialization time.

Example:

<button id="callButton">Call Now</button>
<call-widget button-id="callButton"></call-widget>

Optional Attributes

destination

The destination path for the call, usually in the format "/private/room-name". If not provided, a dialer UI will automatically appear allowing users to enter phone numbers or SIP addresses.

Example:

<!-- Fixed destination -->
<call-widget destination="/private/demo-room"></call-widget>

<!-- No destination - dialer will appear -->
<call-widget token="your_token" button-id="dialButton"></call-widget>

window-mode

Controls the layout and features of the call window. Available options:

• video+transcript: Video call with transcript (default)
• video: Video-only interface
• audio+transcript: Audio call with transcript

Example:

<call-widget window-mode="video+transcript"></call-widget>

log-level

Sets the logging verbosity. Available options:

• debug: Most verbose, includes all logs
• info: General information and important events
• warn: Warnings and non-critical issues
• error: Only error messages (default)

Example:

<call-widget log-level="debug"></call-widget>

user-variables

Custom variables passed as a JSON string. All values must be strings. These variables are attached to the call session and can be accessed on the SignalWire side.

Example:

<call-widget
  user-variables='{"customerName": "John", "accountId": "123"}'
></call-widget>

audio-codec

Comma-separated list of preferred audio codecs.

Example:

<call-widget audio-codec="opus,PCMU"></call-widget>

background-image

Custom background image URL for the call interface.

Example:

<call-widget
  background-image="https://example.com/background.jpg"
></call-widget>

Usage Examples

Basic Audio-Only Call Widget

<button id="audioCall">Start Audio Call</button>

<call-widget
  button-id="audioCall"
  token="your_token"
  destination="/private/audio-room"
  support-audio="true"
  support-video="false"
  window-mode="audio+transcript"
></call-widget>

Video Call with Transcription

<button id="videoCall">Start Video Call</button>

<call-widget
  button-id="videoCall"
  token="your_token"
  destination="/private/video-room"
  support-audio="true"
  support-video="true"
  window-mode="video+transcript"
  log-level="info"
></call-widget>

Dialer Widget (No Fixed Destination)

<button id="dialerCall">Open Dialer</button>

<call-widget
  button-id="dialerCall"
  token="your_token"
  support-audio="true"
  support-video="true"
  window-mode="video+transcript"
  user-variables='{"source": "website"}'
></call-widget>

Call Center Agent Setup

<button id="agentConsole">Open Agent Console</button>

<call-widget
  button-id="agentConsole"
  token="your_token"
  destination="/private/agent-room"
  support-audio="true"
  support-video="true"
  receive-calls="true"
  auto-answer="false"
  window-mode="video+transcript"
  user-variables='{"agentId": "agent123", "department": "support"}'
></call-widget>

Handling Incoming Calls

The widget supports robust incoming call functionality, making it suitable for call center and customer service applications.

Setting Up Incoming Calls

To enable incoming calls, set the receive-calls attribute to "true". You can also configure automatic answer behavior using auto-answer.

<call-widget
  button-id="agentConsole"
  token="your_token"
  destination="/private/agent-room"
  receive-calls="true"
  auto-answer="false"
  window-mode="video+transcript"
></call-widget>

Incoming Call Behavior

When receive-calls is enabled:

1. The widget listens for incoming calls to the specified destination
2. When a call arrives:
   • If auto-answer="true": The call is automatically answered
   • If auto-answer="false": A notification appears allowing the user to accept or decline
3. The call window opens in the specified window-mode once the call is accepted

Events

beforecall

This event is triggered when the call is about to start.

const widget = document.querySelector("call-widget");
widget.addEventListener("beforecall", () => {
  console.log("Call is about to start");
});

beforeDial

This event is triggered before the call is actually dialed, allowing you to approve or reject the call attempt. This is useful for implementing custom authorization or confirmation dialogs.

const widget = document.querySelector("call-widget");
widget.addEventListener("beforeDial", (event) => {
  // Mark that you have a listener (prevents auto-approval)
  event.detail.hasListeners = true;

  // Example: Show confirmation dialog
  const shouldProceed = confirm("Are you sure you want to make this call?");

  if (shouldProceed) {
    event.detail.approve(); // Proceed with the call
  } else {
    event.detail.reject(); // Cancel the call
  }
});

call.joined

Triggered when the call is successfully joined.

widget.addEventListener("call.joined", (event) => {
  console.log("Call joined", event.detail);
});

call.left

Triggered when the call ends.

widget.addEventListener("call.left", (event) => {
  console.log("Call ended", event.detail);
});

call.incoming

Triggered when an incoming call is received (only when receive-calls="true").

widget.addEventListener("call.incoming", (event) => {
  console.log("Incoming call from:", event.detail.caller);
});

user_event

Triggered when custom user events are received during the call.

widget.addEventListener("user_event", (event) => {
  console.log("User event received:", event.detail);
});

JavaScript API

Adding User Variables Dynamically

You can add or update user variables programmatically:

const widget = document.querySelector("call-widget");
widget.newCallVariable({
  customerID: "12345",
  priority: "high",
});

Notes and Best Practices

1. Token Security: Never hardcode your SignalWire token in the HTML. Instead, fetch it dynamically from your server. However, you're free to use click-to-call tokens (c2c_...) statically in HTML.

2. Button Placement: The trigger button can be styled and positioned anywhere in your layout. Just ensure the button-id matches.

3. Window Mode vs Media Support:

   • window-mode controls the layout UI of the widget (purely cosmetic)
   • support-audio and support-video control the actual media features (webcam/microphone usage)

4. Dialer Mode: When no destination is provided, the widget automatically shows a modern dialer interface allowing users to enter phone numbers, SIP addresses, or other destinations.

5. Responsive Design: The widget automatically adapts to different screen sizes and orientations.

6. Best Practices for Incoming Calls:

   • Use auto-answer="false" for agent interfaces where call screening is needed
   • Use auto-answer="true" for automated services or IVR systems
   • For agent interfaces, video+transcript mode provides the most comprehensive call handling experience

7. Call Control: Use the beforeDial event to implement custom authorization, confirmation dialogs, or call screening before calls are initiated.