Well, after enabling the confirmation I see that after a while my device always report busy when trying to send data towards the gateway, in the same way I see on wireshark that after certain time there're no more incoming packtets, which makes sense since the channel seems to be busy and my RB2483 is reporting.
On the other hand, I see now how the payload of the incoming json message seems to be always the same, thing that before removing the end of line was fluctiating...
Still nothing has arrived to my mote from the server side.