Sigfox downlink

How can i connect a node-red downlink by callback to sigfox. I have problems with the url and the data connection. the message is msg.payload={
deviceId : {'data':data}};

Isn't the downlink supposed to work from a callback structure? As in, you set it up in the sigfox settings to send the data towards that address. As configured in the first screenshot, for it to be POSTed to that bluemix address.
The next screenshot however shows an http-request node, which is also trying to access the same address to get data from. But is there an http-in/http-response flow set up on that bluemix server? Or an HTTP server running to accept the callback?

The uplink is working perfectly, but i want to send configuration data to the device at any given time. Does that still require an callback structure? There is an http-in / http-response flow, but can this be used for a downlink only, as it is triggered by a http input!