[AdamJacobMuller]

What I mean more is, once those devices are connected to "the network" is there a way to limit the usage of those SIMs so they could only connect to my systems, and not connect to "the internet" at large.

[webmaven]

Seems like that's something you would design into the device itself (or rather, its software), whitelisting allowed domains or IPs.

[GordonS]

I've done exactly this before when building an IoT device.