Ack message from server

  • Hi!

    I am using a U-Blox SARA0N211 and it connects over UDP and I need the server to respond with an acknowledge message when it receives a message from the device.

    I have been trying to get this working by sending a downlink message to it, however, I am not successful so far.

    My supplier says to ask for: How to set the server to send CoAP 201 message

    I am sure it connects over UDP (it only works when I set it up like that i.e. port 15683 and configured as UDP). Does anybody know if and how to send such an acknowledgment?

    I have tried to send {“resourceValue” : “6441827684813937FF”} downlink, but that does not seem to be working…



  • @David-Netten I don’t think CoAP is supported. Here it says not before february:

    On N211 I believe you can use the neul messenger version of CoAP, which does support acknowledgements. Look for the command AT+NMGS. General tip, try not to build your own acknowledge system.

  • Deutsche Telekom IoT

    @David-Netten be aware the both the CoAP/Leul server and the UDP server are hosted on the same IP But the port of the CoAP/Leul server is 5683 and the port of the UDP server is 15683.

    CoAP/Leul is special CoAP flaviour from Huawei. Some of the Huawei chipset such as HiSilicon which are used e.g. in ublox N211 or Quectel BC95 support it.

    The AT commands for the Quectel BC95 to send and receive messages via CoAP/Leul looks like the following:

    # Read current configuration
    # Set OceanConnect CoAP server and port   
    # Activate send message indicator
    # Send Hello World message
    +NSMI: SENT                                                                      
    # Activate receive message indicator 
    # and display received message 
    # Receive downlink message
    +NNMI: 16,"48616C6C6F20766F6E20536572766572"                                     
    # Activate receive message indicator with message display 

    Regards, Roland

  • hi @Roalnd-Baldin and @Stefan-de-Lange

    Thank you for looking into this. To give a little bit more background:

    I have a temp sensor from a third party (Efento) that has its own operating system. It uses UDP to send a hexadecimal message to a server. I have a working setup with LTE-M sensors and my own server that accepts incoming UDP traffic.

    I am now trying out the new (different) NB-IoT sensors with the cards from IoT creators. As the cards cannot reach public IP’s, I am trying to use the server to forward the CoAP payload to an HTTP endpoint. This is working via

    Now, I look for a way to make the server acknowledge the message. I am not sure how to do this. The only thing I can think of, is sending a downlink message, but I suspect that receiving a (new) downlink message is not the same as receiving an acknowledgment, to the sensor.

    Am I correct that the server is not acknowledging the message?

    Kind regards,


  • Deutsche Telekom IoT


    Hi David,

    you are right, that the UDP server of IoT Creators doesn’t send back an acknowledgment for a received messages.

    BUT: The CoAP/Leul server of IoT Creators acknowledges a received messages with a “2.05 Content” acknowlegment.

    Be aware that CoAP/Leul is the Huawei flavor of CoAP and it is supported by Huawei chipset such as HiSilicon which are used in moduls such ublox N211 or Quectel BC95.

    For many customers it is not enough to have an acknowledgment between the device and the IoT middleware. The implement an asynchronous acknowledgment between the application and the device on the basis of a downlink message. If you would need the asynchnronous application acknowledgment it wouldn’t make a difference between CoAP/Leul and pure UDP.

    Regards, Roland