Fall detection: Apple Watch and iPhone

The Apple Watch does not need a connection to your phone or to the internet to detect a fall. However, your Apple Watch must have a connection in order to call emergency services. It needs to be connected either to your phone, to Wi-Fi with Wi-Fi-calling enabled, or to a cellular network if your Apple Watch is a cellular model.

Hello CrescentGal, Yes Fall Detection needs to be able to connect to iPhone to make the Call. If you won't be with your iPhone always then I would make sure you. get one with Cellular. But it's not fool proof. For Example your in the mountains with weak or no cell coverage the Fall Detection may not be able to make the call.

Use fall detection with Apple Watch - Apple Support