Have you heard that the AppleWatch can be used to make and receive phone calls? It’s true, starting with the AppleWatch Series 3 which Apple introduced in September 2017. That said, there are a few details that one should be aware of.
First, you still need to have an iPhone with an active cellular service plan. This plan also needs to allow you to add a wearable device to it. Think of the AppleWatch as an accessory or add-on for the iPhone.
Second, you need to pay for cellular service for your AppleWatch. Prices vary but as of mid-2018 carriers like AT&T and Verizon typically charge $5 or $10 per month.
Once you have the first two requirements in place, you also need to have your iPhone turned on and it needs to have either a Wi-Fi or cellular connection. It’s important to note that the iPhone does not need to be near your AppleWatch. (This is in contrast to previous AppleWatch models which can send and receive phone calls but only if the iPhone is in very close proximity to the AppleWatch.)
If your AppleWatch has only a wi-fi connection and you want to make a phone call then you need to make sure that Wi-Fi calling is turned on for your AppleWatch. Alternatively you could make a FaceTime audio call.
Apple provides some information about how to make and receive phone calls from an AppleWatch. This information adds more detail than I provide as well as links to related setup instructions.