CFList is not contained in Join Accept Packet

Now, I can join the network with join accept packet.
But in this packet, there is no CFList…

How can I get CFList from network server?
*if I use other network server, my device can receive join accept packet with CFList.
So, I guess, my device firmware is OK.

Region : AS923
Country : Japan.
Router :


Perhaps this is a regional difference issue. Japan requires DwellTime to be limited to 400ms which limits the number of bytes that can be transmitted over the air depending on the data rate used.

A JoinAccept is 17 bytes and with a CFList of 16 bytes would total 33 bytes.

The JoinRequest for AS923 is sent using DR2 (SF10BW125) and default Rx data rate is also DR2. This does not allow a CFList to be sent in the JoinAccept in Rx1 or Rx2 since the maximum payload allowed within 400ms is only 24 bytes.

TTN has correctly limited the downlink according to the selected Country.

Thanks Jason.
How can I get TTN Specification?

In my understanding, AS923 (Asia 920-923MHz) is acceptable to use DwellTime = 0 (No Limit).
So, if select Frequency Plan = Asia 920-923MHz in Gateway Settings, I can select DwellTime = 0 (No Limit).

If there is public document about DwellTime of TTN for each region, I want to read it…


If I recall correctly the channel list is passed as response to the first uplink for channel plans other then Eu868. I’m referring to

Perhaps you need to take a look at the regional parameters to see if the same issue applies to AS915 and at the code to see if TTN uses the same mechanism.

This test code shows Japan values that may be used to configure the TTN backend. Dwelltime is enabled in JP.yml listing.