Inherited GTR 8000 Expandable Site Subsystem - question about backup power - UPS

[soradio]

Hello.

Real newbie question here so apologies for my lack of knowledge. I have inherited 2 of these GTR 8000 and 2 separate locations. Neither of them appears to have any backup battery power as when the power drops even momentarily they go down.
They are under contract and we do have a local provider but our confidence in them is low.
I don't think the units have been serviced in some time.

Each of these GTR 8000 have 3 units in them, like it will hold 6 but we only have 3 with just the 3 power supplies installed at the bottom.

Each of these 3 power supplies has a dedicated 20 amp circuit and the locations have generator power.

Do these GTR 8000 have a built-in battery to act as a UPS? I see reference to a battery and a charger but am unclear if our units are equipped.

When we asked our local provider about a backup battery to cover until the generator kicks in they spec'd us out a 2400-watt 20amp UPS for each GTX. I am hesitant to plug all three power supplies that currently have their own circuits into one UPS on a single 20-amp circuit.

Any help or direction would be really appreciated.
Let me know if this should be posted somewhere else.
Thanks!!