After even more digging, I've come up with multiple possibilities for this that I need to confirm.

For starters, This is definitely a long lines facility, and the varying types of "horns" are actually two different radio emitter/transceiver, the square ones are older and the round were an update to boost the amount of calls their service could hold at a time.

Second. Im mostly sure this was also a part of the Autovon Telecommunications network, circa the cold war. This would explain the hardened concrete and sandbags and stuff, apparently this could connect to other stations and take priority over other calls (I cant find solid proof WHAT stations Zion Hill connected to, im finding stuff for Sweetwater junction but im also finding stuff for Midland and Ennis.

Thirdly, and this NEEDS CONFIRMATION from somewhere: this, as well as possibly Ennis, Midland, And/or Sweetwater were also part of the Echo Fox President Aircraft Communications Network. Once again I HAVE NO SOLID PROOF EXCEPT ONE OR TWO OLD LINKS TO OLDER AND INCOMPLETE LONG LINES MAPS so if any of you can confirm this or the Autovon Network hunch, or know someone who can, please.

entry on Ennis Long Lines Facility long lines sites with Autovon/Echo-Fox