freeswitch/tests/unit/conf_test/gw/test_gateway.xml

<include/>
    <gateway name="test_gateway">
      <param name="username" value="not-used"/>
      <param name="password" value="not-used"/>
      <param name="proxy" value="127.0.0.1"/>
      <param name="register" value="false"/>
      <param name="retry-seconds" value="30"/>
      <param name="dtmf-type" value="rfc2833"/>
      <variables>   
        <variable name="rtp_secure_media"  value="false"  direction="outbound"/>
      </variables>
    </gateway>
</include>