Wow! I’ve been to this a mall a few times. I never really paid much attention to the fire alarm system, but it’s cool to see it in action.
In my hometown, there’s 2 malls. The smaller and closer one had an EST voice evac system installed a few years ago, I’m not sure what was there before.
The larger and busier mall has a Simplex system. I saw at least one 4100U years ago, but it’s likely a 4120 network based off the sheer size of the mall. I think there’s a few videos of this system in action. It played the older 4100+ slow whoop. I’ve been at the mall when the system was silenced (but strobes were flashing).