TTN is a network.
Nodes meant to work with TTN are not TTN, but merely an enabling technology. When used with something else, they aren’t TTN at all.
I never mentioned Premium Gateways, those gateways mentioned are to my understanding in a great extent TTN GateWays.
That seems unlikely, given the range of channels supported. TTN bandplans really assume only 8 channels
Or to put it another way, if your nodes were using TTN, you’d only be worried about the 8 channels in your region’s bandplan.
And I also assume that the IT company is using TTN servers as well for some of its bandwidth.
Again, unlikely - as (unfortunately) there isn’t really any viable scheme for connecting to multiple servers at present.