One of the most-touted features of the Apple Watch is phone calls. But how does it work exactly?

The feature has often been couched as the realization of the two-way wrist radio worn by Dick Tracy, a comic strip character who made his debut way back in 1931.

Apple CEO Tim Cook made reference to the fictional detective’s radio, designed like a wristwatch, in his March 9 keynote introducing the Apple Watch to the world.

“I have been wanting to do this since I was 5 years old,” Cook exclaimed. “The day is finally here.”

Yes, the day is here – to be fair that day arrived a while ago on watches from Samsung, among others. But it’s not quite Dick Tracy because you need an iPhone, too. That’s because the watch does not have cellular capability like the iPhone.

So, why would you take a call on the watch and not the iPhone? There are plenty of examples. A couple of common scenarios might be that you’ve got a bag of groceries in your arms and the phone is in your pocket, or maybe you’re at home and the phone is in another room.

Taking a call is simply a matter of tapping the watch. When a call comes in, you tap the green button icon to “accept” and red to “decline” – just like with the iPhone. Then, to talk, you use the built-in speaker and microphone.

When making calls, Apple's digital personal assistant, Siri, has newfound utility with the watch

For example, just say, “Hey Siri, call Janet” and the watch places the call to the contact. (Note that on the iPhone, Siri has not proven to be as popular as originally anticipated. However because input on the watch is pretty much limited to tapping and voice, Siri can potentially have more utility.)

Using the watch for phone calls at home may be one of its best applications, according to Apple. At the March 9 event, Apple’s Kevin Lynch described how this works.

“Apple Watch communicates with your phone over Wi-Fi as well as Bluetooth. So, when you’re home you don’t have to be within Bluetooth range of your phone. You can be anywhere in your house and still get all of your messages and take your phone calls,” Lynch said.

Where the watch runs up against practicality, however, is in a noisy environment. Talking on the watch can be challenging because of its relatively small speaker. In that case, it may be best to hand off the call to the iPhone.

Or, of course, you can just text. Texting is probably one of the biggest departures from the iPhone because there’s no keyboard on the watch. In that case, you can dictate a message to the watch (which it transcribes) and send. Or, you can send the audio as-is.

Another practical consideration is talk time. The watch is only rated “up to 3 hours” for talking, according to Apple. So, long conversations are best done on the phone, not the watch.

Want to try out all of the above before you place an order for the Apple Watch? Unfortunately, you can’t walk into an Apple store and test the phone feature. That may be doable in the coming weeks as the watch becomes more widely available, according to various Apple store sales associates who were contacted by FoxNews.com.

All in all, the watch should prove to be a helpful extension of the iPhone and, in some cases, a more convenient way to handle calls.