client.calls.create({
  to: "+1" + numbers[i],
  from: process.env.TWILIO_NUMBER,
  url: "https://publicly.accessable/url-of_mine",
  machineDetection: "Enabled",
  method: "GET",
  statusCallback: "https://another.publicly.accessible/url-of_yours?currentIndex=" + i,
  statusCallbackMethod: "GET"
})

const params = event.queryStringParameters;
if (params.CallStatus != 'completed') {
  let i = parseInt(params.currentIndex, 10) + 1;
  client.calls.create({
    to: "+1" + numbers[i],
    from: process.env.TWILIO_NUMBER,
    url: "https://publicly.accessable/url-of_mine",
    machineDetection: "Enabled"
    method: "GET",
    statusCallback: "https://another.publicly.accessible/url-of_yours?currentIndex=" + i,
    statusCallbackMethod: "GET"
  })
}
return Response('')

const params = event.queryStringParameters;
if (params.AnsweredBy == "machine_start") {
    let xml = `
        <?xml version="1.0" encoding="UTF-8"?>
        <Response>
            <Hangup/>
        </Response>`

    client.calls.create( callParameters )

    return Response(xml, mimetype = 'text/xml')
} else{ .. }