Yes. There is a way to setup a private cell using SDR. There was a talk about that in Chaos Computer Club some years ago. I do not remember how they did with the simcards, if they were custom, or normal out of service ones. Caution: because the spectrum band is licensed, it will be automatically illegal pretty much everywhere!

Here a quick search: https://www.reddit.com/r/sdr/comments/1bn1n5f/how_to_run_ope...