@rk Update:
Previous owner removed the IMEI from his account. After that, on the same day, I could send only 1 message; I saw the counter 1 in the dev portal. But then every next message got ERROR and reconnection or even reset didn’t help.

Next day a new attempt; I moved to the other side of the house and got connection at first attempt, and could send data without a problem.

I’m stuck in the “Part I: THE NETWORK ATTACH” manual.

My situation: I’ve a Sodaq NB-IOT shield on a Crowduino connected via serial to my Mac that has Arduino IDE’s Serial Monitor open. Using the serial monitor I can issue the AT commands.

The shield already had a SIM (from someone else). Using that SIM I followed the steps in “Part I” without a problem (using the first IP and hostname). Registered the IMEI in “Part II”, but got stuck in “Part III Hello World” at step 1 that gave an error.

So I removed the power, put the new T-mobile SIM from the NB-IoT Simpack in the Shield, then followed all steps again. Assuming the APN is the ocean connect IP and hostname. Somehow that attempt didn’t got pass “AT+CSQ” that continues to respond “+CSQ:99,99”.

Anything I missed from the manuals or forum?
Thanks, RK