Hello!
I'm looking to make a paging type system at work and not sure if Arduino is the way to go. I work in a factory with a handful of machines and would like to make a way for operators of said machines to call certain people over (supervisors, quality control etc.) with recorded messages. We had a system like this going but one by one the call button boxes have died and the person who programmed them is no longer with the company.
My thought is this: I can use something like the Uno R4 at each machine, which connect through wifi to another one that is hooked up to the PA system. The board connected to the PA could store all the recordings so that the boards at the machines only need to send a signal of "button 1 at machine 1 was pressed".
I might be over my head here...I don't really know how any of this works but would love to learn. I also haven't done a whole lot of research yet so sorry if I haven't given enough information or if the answer is super obvious. I mostly just want to see if its a viable option. Any info would be GREATLY appreciated 
It's surely doable but know that Arduino controllers are not approaved for critical, safety matters.
Assumption - for whatever reason, you don't want visual signals, the easiest/most obvious approach.
Just about any of the ESP wifi devices could read a set of inputs and send a message to another. Keep safety out of the game, though. The audible message can, of course, be only heard through headsets, for example.
In one of my early jobs, the supervisor used red - machine failure, yellow - need attention, critical, green - need attention, not critical, and white - out of raw material, IIRC, flags to do what you want. Machines were a line of metal lathes and other metalworking equipment; super could look out office window and see at a glance what was what. Super cheap, failproof.
Two quick thoughts.
The UNO R4 is a big board intended for learning. A smaller board would be better.
The esp-now protocol is easier to use than wifi and has a range of 220m.
Lora has longer range if line of sight but tradeoffs re range, bandwidth, data size.
Sparkfun sells a device called the Wav Trigger that should do what you want out of the box IIRC. Otherwise you can use a DF Mini player and a bit of circuitry. No need for an arduino in this application.
[Edit]
It seems that you might want this to be wireless. The popular RF keyfobs should enable wireless buttons depending on how many you need.
Thanks so much everyone! You've all given me plenty to look into so I'm going to take some time doing just that and see how far I get 
