Transfer call and recording

Can someone explain how can I send transfer call record to my server? Im using Nexmo.

Here is what I have for answer_url parameter:

<vxml version = "2.1">
    <form id="CallTransfer">
        <block>
            <prompt>Hello</prompt>
        </block>
        <transfer name="MyCall" dest="tel:+'.$number.'" bridge="true" connecttimeout="20s"/>
        <record name="recording" beep="false" finalsilence="3s" maxtime="240s">
            <catch event="connection.disconnect.hangup">
                <submit next="http://'.$_SERVER['SERVER_NAME'].'/api/save_call/'.$history_id.'" method="post" namelist="recording" enctype="multipart/form-data"/>
            </catch>
            <filled>
                <submit next="http://'.$_SERVER['SERVER_NAME'].'/api/save_call/'.$history_id.'" method="post" namelist="recording" enctype="multipart/form-data"/>
            </filled>
        </record>
    </form>                
</vxml>

But its send empty $_FILES array on /api/save_call.

Also, I have a question, is it possible to get call record starting when first abonent picked up the phone and ending when second is hangup?

Currently, it's not possible to record a transfer using native VXML. As Kevin points out, that just not something VXML supports.

We (I work at Nexmo) know there are use cases that require that support, and it is something we're working on.