Mocking LTE-M and/or NB IoT connection


I cannot connect to the NB IoT in Serbia with an iBasis SIM card. This is a significant limitation for my dev work because I can't test any part of the software that talks to the internet.

I've been wondering if there is a way to set up a local NB IoT or LTE-M network. Then, this network could connect to some wifi to provide proper networking.
Alternatively, do you maybe have a mock of the LTE Link control library that could enable the rest of the code to act like it has an LTE-M or an NB IoT connection while it doesn't have it?

I'm unsure how to proceed here, so any help would be tremendous.

Best Regards,