Issues with NB-IoT


I have been trying to connect a gNB (Amarisoft Callbox Mini) where I deployed an NB-IoT cell to Free5GC. When the AMF receives the NGSetupRequest from the gNB, I get the following error message: “NGAP decode error : OpenType reference value does not match any field”.

I think this is due to the presence of the “id-NB-IoT-DefaultPagingDRX” protocol IE in the NGSetupRequest. It looks like all of the protocol IEs supported are declared here but NB-IoT-DefaultPagingDRX is not in there.
So I think it is why there is an NGAP decode error.
Here is a Wireshark file where I captured the NGSetupRequest (you can apply ngap filter to see it) ng_setup_request.pcap (2.5 KB)

NB-IoT-DefaultPagingDRX for NGAP is defined in the TS 38.413, and its presence is marked as mandatory.

If NB-IoT is not supported, do you plan to support it in the future ?

Best regards,


Hi Nicolas,
it seems that NB-IoT Paging and eDRX aspects has been introduced in TS 38.413 in Release 16.2.0. Free5GC is R15 and beyond so I think too that NBIoT is not implemented yet. But it will be eventually (as stated in the project roadmap) after R15 is fully implemented.

Hi, my bad I didn’t see that NB-IoT Paging was introduced in Release 16.2.0, thank you for your answer !