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There is some information here: https://forum.iotcreators.com/topic/733/how-long-will-a-downlink-message-stay-in-the-network-queue

@hans-liefting Hi Hans.

Our device registers itself every hour at the network, after which it will send an uplink message.

What protocol are you using? I would definitely not recommend to register every hour. Registering with the network is very costly energy consumption wise since many messages are exchanged. So unless your module has a very poor PSM mode the tradeoff is not worth it. Operators also generally don’t like it since it creates more load on the network.

When the device sends the uplink message, our backend replies with a downlink message that is delayed by a maximum of 3 minutes.

I am not entirely sure but I don’t think this will work since the downlink message has to be queued before you sent the uplink… but t-mobile will know the details on that.

After the uplink message has been successfully sent, the modem waits for 10 seconds for a downlink message. Afterward, it closes the connection and shutdown the modem (we use the Telit modem ME310G1-WW).

My guess is that when the modem deregisters itself from the network, the downlink message queue is cleared. But again t-mobile has to confirm this…

Note that for energy reasons, our device does not go to PSM but actually shuts down.

Can you please try again without shutting down but staying in PSM mode?

@florian-duecker test123

edit: works

@Florian-Duecker said in Edit forum posts, after posting:

Would be happy to get some feedback if this works.

Doesn’t work yet unfortunately.

@Florian-Duecker said in Edit forum posts, after posting:

within the first hour after posting.

Why only within the first hour?

@magnatron It can work ofcourse but in general NB-IoT was not designed to handle so much data

@magnatron Because 75KB is too much for NB-IoT. It’s better suited for LTE-M

@magnatron if you have 75KB to send to a device you should probably switch to LTE-M…

Editing never worked, also deleting never worked

@magnatron said in Collegial roaming?:

The signal quality hovers at 99,99 when a modem doesn’t find an MT to connect to. Once it finds an MT and is able to connect the signal quality will indicate RSSI and QUAL.

I understand. But CSQ tells you nothing about the ability to connect, it’s just an indication that there is a signal.

In my experience, on band 8 this is no problem and happens almost instantly. Tested in The Netherlands and in Germany.

I have also not had any problems. Perhaps it is a modem issue? You can try u-blox or nRF91, those are very reliable in my experience.

But on band 20, in NL only available through VL, auto-COPS (AT+COPS=0) doesn’t work. The device will only connect when COPS is specified via AT+COPS=1,2,"20404".

You mean you are trying to roam on band 20 VFNL NB-IoT using a T-Mobile sim?

@magnatron Is this for NB-IoT? As far as I know T-Mobile NB-IoT is not available on band 20 in NL.

@magnatron said in Collegial roaming?:

On band 8 auto-COPS works fine but on band 20 I have to set COPS to 1,2,“20404” before the CSQ goes below 99,99.

I don’t understand this part, the COPS command will force it to vodafone. What do you mean by CSQ goes below 99,99?