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After the Google Home smart speaker got some additional smart home device partners earlier this week, August became the first smart lock company to work with all three major voice control platforms -- Apple HomeKit, Amazon Alexa and Google Home. This is good news for customers who haven't yet pledged loyalty to a Siri-, Alexa-, or Google Assistant-specific smart home. It also likely means voice control coming to more and more security-centric smart home devices.

With the convenience of voice commands, come some safety concerns. Is it really a good idea to use your voice to lock or unlock your door? Here's a look at the role of voice control as it applies to smart locks, the August Smart Lock in particular, and some advice on how to be smart about using your voice to lock and unlock your door.

The smart lock landscape

August, Kwikset, Schlage and Yale are among the most well-known smart lock manufacturers today. Here's an overview of the voice-enabled locks/deadbolts they sell and the platforms they support:

August

Kwikset

Schlage

Schlage Sense - HomeKit

Schlage Connect - Alexa (with SmartThings or Wink)

Yale

Yale Real Living Assure - HomeKit (with the Yale Network Module), Alexa (with SmartThings or Wink)

Yale NexTouch Wireless - HomeKit (with the Yale Network Module)

Since the second-gen August Smart lock works with HomeKit, Alexa and the Google Home, I used one installed in the CNET Smart Home to test out the nuances of each voice control platform.

The voice control landscape

Amazon Alexa

Amazon's Echo and Echo Dot are both fixed devices that you plug directly into the wall. The more mobile Tap runs on a battery and it launched with a push-to-talk function only, but it can also act like an Echo or a Dot when it's on its charging dock and you enable its new always-listening mode. Alexa devices don't have to be on the same Wi-Fi network as the smart devices you want to control. You can also access Alexa remotely via the Amazon app on your iOS device. Thanks to that new feature (and to a lesser extent, the portability of the Tap), you can now ask Alexa to unlock your door from pretty much anywhere.

Amazon offers voice control integrations with a variety of companies through it's Alexa Skills Kit. This is where you search on the Alexa app or on Amazon.com for the skill you want. August has both a custom and a native skill with Alexa.

With the custom skill, you can say, "Alexa, ask August to lock/unlock the office door." But, you have to give Alexa a custom PIN code in order to complete the command. Make sure not to say the code near anyone you wouldn't want to hear it and don't pick something obvious like 1-1-1-1 or 1-2-3-4 and you should be fine. With the native phrase, you can shorten the sentence to, "Alexa, lock the office door," but it doesn't currently support a native unlocking command, you have to use the "ask August" step.

Apple HomeKit

Enlarge Image Chris Monroe/CNET

HomeKit voice control via Siri is mostly a push-to-talk experience, in contrast to the always-listening Echo and Google Home. You need to push your iPhone's home button, or the dial on the side of your Apple Watch to bring up the Siri interface before you can give a command.

Siri does have the "Enable 'Hey Siri'" option, which removes the push-to-talk requirement from newer iPhones, but the iPhone's microphone won't pick your voice up if you're more than a few feet away. An Amazon Echo or a Google Home smart speaker will hear you from across a room.

With Siri in either mode, you can use your voice to both lock and unlock a second generation August Smart Lock. You can also include either the lock or unlock functions as part of a HomeKit scene, which is a voice or app-driven command that triggers a set of actions on multiple smart home devices at once. For example, at the CNET Smart Home we use the phrase "Lockdown" to close the blinds, shut off the lights, and lock the door.

There's no passcode or other additional security steps that you have to deal with if you're unlocking your door with Siri. And because you need an iOS device close at hand to issue the command, there's less of a concern about someone shouting from outside and actually unlocking the door. They'd have to get a hold of your iOS device and defeat whatever lock you might have on it before being able to control your door.

The exception is if you have your phone in passive "Hey Siri" mode, which will respond to anyone who uses the "Hey Siri" wake phrase.

Google Home

The August Smart Lock is the first connected lock to work with the Google Home. While Google plans to add an unlocking door command later this year, today you can only lock the door or ask for the status of the lock. Because of this limitation, there aren't as many security concerns related to using the Google Home to control your August Smart Lock. No one would be able to unlock the door by shouting from outside, for instance.

Convenience over security?

I asked August what they'd say to a customer who's considering a smart lock, but who also has reservations about voice control. From August CEO Jason Johnson:

"Using a person's voice to unlock a door should only be implemented in a secure manner such as with a unique PIN, password, or other method of authenticating the user."

Authentication is a must on the technical side, but there's a human element in play that also needs consideration. Standard "don't tell anyone your PIN/password, don't use easy-to-guess numbers or phrases" advice applies, but speaking your code out loud invites more opportunities for exposing your credentials. A few additional suggestions:

Use a password, fingerprint or equivalent mechanism to secure access to your phone.

Be aware of anyone who might be listening when you say the PIN code for your lock.

If you live in a dense residential area, be aware of any open windows and thin walls at home.

The benefits of using voice both in and outside of your home to control your door lock are many, but as a general rule, any new method for you to control your door (or anything else) is a method someone else can exploit. Give it some thought before you dive in.