While setting up my Multitech gateway I decided to remove the lines in the config that enables upload to Semtech. During testing of the network using a RN2483 module I saw that the module responds with only "ok" when I do a "mac tx cnf". Then the node will wait for either a "mac tx ok" or some other failure response. But this never happens. At first I thought the problem was with my RN2483's firmware, but after a upgrade I got the same issue.
Researching the issue pointed to a few comments on this forum hinting that TTN does not yet support acknowledgements:
I therefore changed my gateway's configuration to include the Semtech server again. This enable acknowledgements to be sent. Now my node can be sure the message did transmit successfully.
Are my assumptions correct about TTN not sending acknowledgements?
Maybe the Wiki entries for gateway setups should clearly state that uploading to Semtech is necessary for acknowledgements.