Initiating an outbound call using Twilio Function

      twiml.dial(dialNode => {
      dialNode.conference('Test conference', {
        startConferenceOnEnter: true,
        endConferenceOnExit: false,
        from: context.CALLER_ID,
        to: event.TO
      })

I have tried this on Twilio Functions but this returns an error on the client side.

There are quite a few Twilio Function examples, one of which is making an outbound call. You can view the examples here (under Function Examples) on the left side of the screen.

Make a Call

// Description
// Make a call

exports.handler = function (context, event, callback) {
  // Make sure under Functions Settings tab:
  // "Add my Twilio Credentials (ACCOUNT_SID) and (AUTH_TOKEN) to ENV" is CHECKED

  const twilioClient = context.getTwilioClient();

  // Pass in From, To, and Url as query parameters
  // Example: https://x.x.x.x/<path>?From=%2b15108675310&To=%2b15108675310&Url=http%3A%2F%2Fdemo.twilio.com%2Fdocs%2Fvoice.xml
  // Note URL encoding above
  let from = event.From || '+15095550100';
  // If passing in To, make sure to validate, to avoid placing calls to unexpected locations
  let to = event.To || '+15105550100';
  let url = event.Url || 'http://demo.twilio.com/docs/voice.xml';

  twilioClient.calls
    .create({
      url: url,
      from: from,
      to: to,
    })
    .then((result) => {
      console.log('Call successfully placed');
      console.log(result.sid);
      return callback(null, 'success');
    })
    .catch((error) => {
      console.log(error);
      return callback(error);
    });
};