Larry...on the tower in my backyard a third provider just added panels. They are thicker, so I doubt its Sprint. Village hall has no idea who threw panels up there. I guess they didn't need a permit (but they jam one down your throat for everything else here). Is there a site that lists permits for those to operate, ie FCC? I bet its at&t or Verizon (both 850) here.
For most cell sites there's nothing online that can tell you who they are. Sometimes towers are FCC registered and you can look them up here: ASR Registration Search But I doubt any co-location sites would be on there as it's usually just certain towers.
sometimes it does, sometimes it does not. make sure you are clicking the antenna listings, not tower. there are several in my area that list multiple carriers