[123919239]

Yes you need to burn a SIM card, but that's it basically. srsLTE and other "homebrew" eNodeB software is standards-compliant and your smartphone will most likely connect.

In practice, you need to worry about legal restrictions -- you're not allowed to transmit on common LTE bands.

Not sure how this will actually look in the future. Is the office mobile network physically separated, or do you use the public network with special SIM cards that connect to a virtually separated mobile network?

[Jhsto]

One idea is that commercial installations rely on unlicensed spectrum (like 6Ghz) to transmit LTE. Check out MuLTEfire for this. As far as I know, there are no LTE base stations transmitting these frequencies available for purchase.

With 5G some countries have also taken into concern a more liberal spectrum policy, which could result in more mobile network operators. One idea follows is that the spectrum would be "oversold" by selling the same frequency to organizations tied to particular cities, for example.

Finally, there is the notion of virtual SIM cards. And as far as I know, alternatively you could also just hack the LTE server to accept each incoming connection (with any SIM) and use a challenge after the Internet connection is established, and then just kick out any device which doesn't send the magic packet.

[sargun]

Yeah, the idea was to use ISM band. The problem was finding MTs that supported these bands. The LTE base station was much easier.

I was hoping 5G had taken this use case into account, and thought to optimize for those bands, or alternatively allow for use of 60 GHz, or something where i can get a local license for usage of that band.

[123919239]

You cannot accept unknown SIM cards due to mutual authentication -- the provider must know the shared secret that is burned into the SIM.

You can achieve network separation APNs, so there is no need for such a hack.

The question I have in mind is: Does your office advertise it's own PLMN with WiFi-like equipment, or do you outsource your office wireless network to an established operator which handles authentication and provides a virtual, separate network?

[Jhsto]

Oh nice to know the thing about the SIM cards!

Regarding your question, I recall reading a paper which compared both cases: the office owning the whole infrastructure, and one in which it is rented/outsourced to an established MNO. While the paper suggested that both use-cases are plausible, in practice your preference is likely to vary depending on local regulation and use-case (e.g. latency requirements etc.).