gistfile1.xml

    <flow name="sendSmsMessage">
        <vm:inbound-endpoint address="vm://sendSms" />
        <twilio:send-sms-message from="${from.number}" 
                                 to="#[map-payload:to]" 
                                 body="#[map-payload:body]" 
                                 status-callback-flow-ref="callbackFlow" />
    </flow>

    <flow name="callbackFlow">
        <logger message="Callback received: #[payload]" />
        <!-- handle the callback -->
    </flow>