Extra channel in network server

Can someone clerify what the significance of the extra channel configuration in the network server (toml)?
I tried to connect dragino lt-22222-l device with IN865 region.
The network accepted the uplink messages only after adding extra channels
Does it means that the device is using a frequency that is not under the Lora frequency plan? why ?
So when do we need extra channels?

That seems odd, you should not need extra channels for IN865, what channels are those?

Extra channels are used for example in EU868, where you have 3 basic channels which device must support. Then you have 5 most commonly used extra channels, which are not strictly required, but it is good practise to use them.

Thank Martin for the quick response.
So IN865 there are only 3 basic channels with no commonly used extra channels?
To your question - the device is trying to send a first Uplink message at freq 865.62.
I add just for testing the following extra channels : 865400000,865600000,865800000,866000000,866200000,866400000,866600000,866800000
And it work all the time.

So IN865 there are only 3 basic channels with no commonly used extra channels?

Seems like it, but don’t take my word for it. It also doesn’t restrict you from using extra channels too (if those are compliant with local radio equipement regulations).

I suggest you to take a look at LoRaWAN Regional Parameters document. From that I can see the device with IN865 must support these channels [MHz]: 865.0625, 865.4025, 865.9850, which does not fit anything you listed.

I would double check which channel plan is set on the device. And probably on the gateway too.