object Twilio extends RestHelper {
  serve( "api" / "twilio" prefix {
    case _ => () => {
      Full(XmlResponse(<Response><Say>Goodbye!</Say><Hangup/></Response>))
    }
  })
}

curl -XPOST --dump-header - http://localhost:8080/api/twilio
HTTP/1.1 200 OK
Expires: Tue, 31 Jan 2012 05:11:22 GMT
Content-Length: 101
Cache-Control: no-cache, private, no-store
Pragma: no-cache
Date: Tue, 31 Jan 2012 05:11:22 GMT
X-Lift-Version: 2.4
Server: Jetty(7.4.5.v20110725)

<?xml version="1.0" encoding="UTF-8"?>
<Response><Say>Goodbye!</Say><Hangup></Hangup></Response>