Sorry for the late answer. This is a question we don’t have a simple answer to yet.
We experience that it often helps to remove the plastic caps on RTS and CTS on your expansion board.
You should also check that the antenna and sensor-pins are in the correct slots.
If none of the above works we recommend you try with another SIM card. You can order a new free SIM card here: Start IoT SIM card
I hope one of the above solutions will solve the problem.
Keep us posted, and we will investigate further to find other possible solutions.