The twilio.js Library: Twilio.Connection (1.4)

A Twilio.Connection object represents a call to or from Twilio. You never instantiate it directly, but it's passed to event handlers and returned when you call Twilio.Device.connect().

// Explicitly create a new outgoing connection
var connection = Twilio.Device.connect();

// or handle an incoming connection event
Twilio.Device.incoming(function(conn) {
  // conn is a Twilio.Connection object
});

Method Reference

The following is a list of methods available on a Twilio.Connection object. The .accept() and .disconnect() methods behave similarly to jQuery's click method. When passed a function, these methods register that function as a handler to be called when an event occurs. Calling the method without passing a function triggers that event handler.

.accept( [audioConstraints] )

Accepts an incoming connection.

This will begin establishing the media session to this device. The connection status will be set to connecting while the media session for the call is setup. The connection status will change to open once the media session is established.

Twilio.Device.incoming(function(conn) {
  conn.accept();
});

You can optionally specify an audioConstraints object to change the behavior of the local media stream during this call. You can use this to select a specific microphone, or turn off features like auto-gain control. Each web browser implements a different set of MediaTrackConstraints which may be used as audioConstraints, so consult your browser's implementation of getUserMedia for further details.

var audioConstraints = {
  optional: [{ sourceId: 'XXX' }]
};

Twilio.Device.incoming(function(conn) {
  conn.accept(audioConstraints);
});

.accept( handler(connection) )

Register a handler function to be called when this connection object has finished connecting and changes its state to open.

The handler function receives the Twilio.Connection object as its sole argument.

.reject()

Reject a pending connection. This will cause a hangup to be issued from the client session to the dialing party. If multiple client sessions are active the pending connection will be rejected for all of them.

.ignore()

Ignore a pending connection. This will stop the Client device from playing the incoming sound and set the connection state to closed, but will not send a hangup message to the dialing party. The incoming call will keep ringing until another Client with the same name answers the call, or the call times out.

.disconnect( handler(connection) )

Register a handler function to be called when this connection is closed.

The handler function receives the Twilio.Connection object as its sole argument.

var connection = Twilio.Device.connect();

connection.disconnect(function(conn) {
  console.log("the call has ended");
});

.disconnect()

Close this connection.

.error( handler(error) )

Register a handler function to be called when any device error occurs during the lifetime of this connection. These may be errors in your request, your capability token, connection errors, or other application errors. See the Twilio Client error code reference for more information. Using the error handler is a great way to debug your application and help catch mistakes in your code!

The handler function receives an error object as an argument. The error object may include the following properties:

Property Description
message A string describing the error.
code A numeric error code described in the Twilio Client error code reference.
connection A reference to the Twilio.Connection object that was active when the error occurred.

.mute(bool)

Mutes or unmutes the current connection based on the boolean parameter you provide. true mutes the connection by ending audio gathered from the user's microphone, false unmutes the connection.

.mute( handler(boolean, connection) )

Register a handler function to be called when a connection is muted or unmuted.

The handler function receives a boolean indicating whether the connection is now muted (true) or not (false), and the Twilio.Connection object that was muted or unmuted.

.isMuted()

Returns a boolean indicating whether the connection is muted.

.getLocalStream()

Get the local MediaStream being used by the Connection. This contains the local Client's audio input.

.getRemoteStream()

Get the remote MediaStream. This contains the remote Client's audio, which is being received locally and output through the local Client's speakers.

.sendDigits( digits )

Play DTMF tones. The digits parameter is a string and can contain the characters 0-9, *, #, and w. Each w will cause a 500 ms pause between digits sent. If you're familiar with TwiML, you can think of the sendDigits method as the sendDigits attribute in the <Number> noun. The SDK only supports sending DTMF digits. It does not raise events if DTMF digits are present in the incoming audio stream.

.status()

Return the status of this connection. The status will be one of the following strings:

Status value Description
"pending" The connection is incoming and hasn't yet been established.
"connecting" The connection has been accepted by or initiated by the local client.
"ringing" The callee has been notified of the call but has not yet responded.

Note: As of 1.4.25, this state is only surfaced when the enableRingingState flag is set to true in Device.setup options and the TwiML app is dialing out with the answerOnBridge property, eg: <Dial answerOnBridge=true></Dial>.
"open" The connection has been established.
"closed" The connection has been disconnected.

.postFeedback(score, issue)

Posts the feedback collected for this call to Twilio. If no parameters are passed, Twilio will report feedback was not available for this call. Posting the feedback using this API will enable you to understand exactly which factors contribute to audio quality problems. Twilio will be able to correlate the metrics with perceived call quality and provide an accurate picture of the factors affecting your users’ call experience.

Scores
Score Suggested Interpretation
1 Terrible call quality, call dropped, or caused great difficulty in communicating.
2 Bad call quality, like choppy audio, periodic one-way-audio.
3 Average call quality, manageable with some noise/minor packet loss.
4 Good call quality, minor issues.
5 Great call quality. No issues.
Issues
Issue Name Description
dropped-call Call initially connected but was dropped
audio-latency Participants can hear each other but with significant delay
one-way-audio One participant couldn’t hear the other
choppy-audio Periodically, participants couldn’t hear each other. Some words were lost.
noisy-call There was disturbance, background noise, low clarity.
echo There was echo during call.
Examples
.postFeedback(5); // Perfect call!
.postFeedback(2, 'dropped-call'); // Not so perfect... We'll do better next time!
.postFeedback(); // We asked the customer for feedback but they declined to provide feedback.

.volume(handler(inputVolume, outputVolume))

Register a handler function to be called with the Connection’s current input volume and output volume on every animation frame. The handler will be invoked up to 60 times per second, and will scale down dynamically on slower devices to preserve performance. The handler receives inputVolume and outputVolume as percentages of maximum volume represented by a floating point number between 0.0 and 1.0, inclusive. This value represents a range of relative decibel values between -100dB and -30dB.

Event Reference

#ringing

.on('ringing', handler(hasEarlyMedia))

Note: This feature is behind a flag on Device.setup: enableRingingState. By default, this event will not fire.

Raised when the Connection has entered the ringing state. By default, TwiML's Dial verb will connect immediately and this state will be brief or skipped entirely. When using the Dial verb with answerOnBridge=true, the ringing state will begin when the callee has been notified of the call and will transition into open after the callee accepts the call, or closed if the call is rejected or cancelled.

The hasEarlyMedia argument is a boolean denoting whether there is early media available from the callee. If true, the Client SDK will automatically play the early media -- Sometimes this is ringing, other times it may be an important message about the call. If false, there is no remote media to play, so the application may want to play its own outgoing ringtone sound.

Example
connection.on('ringing', function(hasEarlyMedia) {
  showRingingIndicator();
  if (hasEarlyMedia) { playOutgoingRinging(); }
});

#warning

.on('warning', handler(warningName))

Raised when a call-quality-metric has crossed a threshold.

Twilio.js raises warning events when it detects a drop in call quality or other conditions that may indicate the user is having trouble with the call. You can implement callbacks on these events to alert the user of an issue.

For a full list of warning events, check the Voice Insights events reference. Check the examples below to see how to listen to warning and warning-cleared events.

Example
connection.on('warning', function(warningName) {
  if (warningName === 'low-mos') {
    showQualityWarningModal('We have detected poor call quality conditions. You may experience degraded call quality.');
  }
});

#warning-cleared

.on('warning-cleared', handler(warningName))

Raised when a call-quality-metric has returned to normal.

Example
connection.on('warning-cleared', function(warningName) {
  if (warningName === 'low-mos') {
    hideQualityWarningModal();
  }
});

Property Reference

.parameters

.parameters contains details about the call, such as who is calling and what was dialed. The meaning of these parameters matches those in the Twilio Voice request parameters.

Incoming .parameters

On incoming connections, the following parameters are included:

Parameter Description
CallSid A unique identifier for this call, generated by Twilio.
AccountSid Your Twilio account ID. It is 34 characters long, and always starts with the letters AC.
From The phone number or client identifier of the party that initiated the call. Phone numbers are formatted with a '+' and country code, e.g. +16175551212 (E.164 format). Client identifiers begin with the client: URI scheme; for example, for a call from a client named 'tommy', the From parameter will be client:tommy.
To The phone number or client identifier of the called party. Phone numbers are formatted with a '+' and country code, e.g. +16175551212 ( E.164 format). Client identifiers begin with the client: URI scheme; for example, for a call to a client named 'jenny', the To parameter will be client:jenny.
ApiVersion The version of the Twilio API used to handle this call. For incoming calls, this is determined by the API version set on the called number. For outgoing calls, this is the API version used by the outgoing call's REST API request.
Outgoing .parameters

On outgoing connections, the following parameters are included:

Parameter Description
CallSid A unique identifier for this call, generated by Twilio.

Deprecated Methods

The following methods have been deprecated and will be removed in a future release of twilio.js. Calling these methods will generate a deprecation warning unless the warnings parameter is set to false when calling Twilio.Device.setup().

.mute()

Stop capturing audio from the microphone for this connection. This method has been replaced by .mute(bool).

.unmute()

Resume capturing audio from the microphone for this connection. This method has been replaced by .mute(bool).

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