Do I need a POTS line for 911 service for shared facilities?

More specific:

I've got two facilities about 10 miles from each other, connected directly to each other with fiber. Basically setup to be a long ethernet cable.

The phone systems at each facility can communicate to each other freely. More or less, when a phone call goes out from facility 2, it's routed back to facility 1 and then hits the outside world.

Is there a way to have the address information at facility 2 to populate if someone dials 911? Or will it only display the information for facility 1? I've been told that I need a POTS line at facility 2, but I've also been told I didn't. Not sure who's right.

Thanks folks.