This is a unique and specific one that won't apply to many but maybe help at least one. My wife has limited mobility and other chronic health issues. My shop is detached from the house. If she needs me she calls or texts but there are times when I just don't hear the phone or see the text. I put an amazon alexa in the shop and bought some of the smart plugs that communicate with it. I put the smart plug on a big red light bulb in center of my shop on top of my bandsaw. If you say "alexa, turn on lamp" the red light comes on and I can see or notice it easily no matter what I'm doing. It's a backup for if I don't answer my phone and she really needs help. I considered ear buds and bluetooth etc but it's something I have to remember to connect and put on, etc. And I don't like ear buds. This setup doesn't depend on me remembering.