The real issue is certification and so on. The people running small cellular networks tend to have necessary permissions or operate within certain limits. For

The real issue is certification and so on. The people running small cellular networks tend to have necessary permissions or operate within certain limits. For public, general usage baseband, it will need to be at least tamper evident and you won't be able to just run your own. I'd personally be fine with auditable baseband (i.e. you can always verify what code it runs, then let's say compare to public code tree and build hashes), with possibly a signature scheme that would link builder and certifications. Then if you went to the trouble of proving you have the necessary qualifications and won't break shit, you could sign with your own certificate and take responsibility.