You can think of a video doorbell as a "caller ID" for your home, using a camera and internet connection to show you who is at the door before you answer it. And the great thing is, while that is handy if you don't want to budge from the sofa unless you have to, it also means you can see and speak to visitors from anywhere in the world. And for some models, unlock the door from the same video call too.

Despite feeling like a gadget from the future, video doorbells are remarkably simple. They look and operate much like a regular doorbell, and can even be powered by the same wiring in some cases. They include a camera, microphone, and speaker to allow for a two-way conversation between the doorbell and its companion smartphone app. You can also set up the doorbell to ring a chime plugged into a wall outlet (just like a regular doorbell), or even make an announcement via a smart speaker in the home. That way, Alexa can announce that someone is at the door.

Read More:

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• How to ask Alexa to answer your Ring Video Doorbell Pro

Another key feature is how video doorbells can act as security cameras, triggered by motion and recording video to the cloud – a video that is HD color during the day and infrared night vision after the sun has set.

Despite their many features, video doorbells are priced from around $60, while the majority of options are between $75 and $200, and some stretch that up to around $250.

GearBrain thinks these five questions are a good place to start and will help you find the right smart video doorbell for your smart home:

1. How is it installed and powered?

Instructions from Amazon for installing a Ring video doorbellAmazon

Most video doorbells are designed to fit in the same place as your existing non-smart doorbell. In many cases, they also connect to the same wiring and can draw enough power to function with the wire used by the previous doorbell. You will often find everything you need in the box, and only very basic DIY skills are required. For example, the $65 Ring Video Doorbell Wired comes with a jumper cable to isolate the existing chime, and the doorbell unit itself connects to the wires already installed by your front door.

Other options can be made to work with your home's existing chime. However, companies like Ring also sell their own wireless chime for connecting to a wall outlet, or you can make do with the doorbell ringing your smartphone or smart speaker.

Some video doorbells are wireless. This makes installation even easier (just attach it to your home with the included screws and mounting kit), but means you'll need to recharge its battery every few weeks. This isn't difficult but can be annoying if you ever forget and are left without a working doorbell until the battery has been topped up.

Blink Video Doorbell | Two-way audio, HD video, motion and chime app alerts and Alexa enabled — wired or wire-free (Black)

List Price: $49.99

New From: $49.99in Stock

Used From: $35.29in Stock

2. How do you know if someone is at the door?

The Nest Hello has a tall aspect ratioGoogle

This question isn't as daft as it might sound. As we mentioned earlier, some smart doorbells don't work with your existing chime. So, unless you buy a new wireless chime then pressing the button will not make a noise in your home. Instead, you'll need to get used to your smartphone alerting you to visitors. You can also set the doorbell to alert you to motion, such as when someone is loitering nearby, and even automatically record a few seconds of the footage when motion is spotted. These systems often need fine-tuning, as passing vehicles or a neighbor's cat can cause a false alarm until you have calibrated the camera's sensitivity and field of view correctly.

We recommend setting up the doorbell so that it alerts your phone when someone presses the button but also rings a chime so that you'll be notified even if your phone is on silent, switched off, or in another room.

Ring Video Doorbell 4 – improved 4-second color video previews plus easy installation, and enhanced wifi – 2021 release

List Price: $219.99

New From: $219.99in Stock

Used From: $136.36in Stock

3. How resistant to theft and water are video doorbells?

Most of today's video doorbells are weather resistant. For example, looking again at the entry-level $60 option from Ring, Amazon claims it is weather resistant and designed to operate in temperatures ranging from -5F to 120F.

As for theft, this can depend a little on how the doorbell is installed. They all come with mounting screws and brackets to secure them to the wall or door frame, but if a thief was determined enough they could feasibly break the device away from its mounting. This would take a lot of effort – and remember, they are trying to steal a security camera, on your front door, and with a clear view of their face. The device would alert you to motion long before they manage to remove it.

4. Why are some video doorbells more expensive than others?

The flagship Ring Pro 2 is priced at $250Amazon

Another good question, as on the face of it many of these devices work in a very similar way. Let us look at the Ring range to play a game of spotting the difference between the $60 and $250 options.

The more expensive Ring model records video in higher 1536p resolution, compared to the 1080p or its cheaper siblings. It also has a more advanced motion detection system, works with your existing chime box, has dual-band Wi-Fi and Alexa greetings, plus the option to change the face plate for a different color, and a broader view for seeing from a visitor's face to the ground. The latter makes it useful for checking on parcels left on your doorstep. Lastly, the more expensive model has improved audio over other versions.

We admit this isn't a huge list of must-have features, and the cheaper option (or mid-range $170 Ring Pro) would suit the needs of a great many smart home users. The flagship Pro 2 would only be worth it if you really value HD audio and that head-to-toe viewing angle. Meanwhile, the Google Nest Video Doorbell is less expensive but features a tall viewing angle, plus HDR video quality for only $100.

Google Nest Doorbell (Wired) - Formerly Nest Hello - Video Doorbell with 24/7 Streaming - Smart Doorbell Camera for Home with HDR Video, HD Talk and Listen, Night Vision, and Person Alerts

List Price: $99.99

New From: $94.89in Stock

Used From: $78.95in Stock

5. Is the video doorbell compatible with my smart home?

We have mostly focused on Ring doorbells in this article, but there are many other options from companies like August, Nest, Skybell, and Blue. Naturally, Ring doorbells work best with an Alexa smart home system and the Nest Hello is best suited to a Google Home setup. But options from companies like Netatmo, Robin, and Yobi work with Apple HomeKit, and doorbells by Eufy work with the company's own app (as well as Alexa).

Smart Video Doorbell Buying Guide - GearBrainwww.youtube.com

Arlo Essential Video Doorbell Wire-Free |HD Video, 180° View, Night Vision, 2-Way Audio | 6-Months Battery Life | Direct to Wi-Fi, No Hub Needed | Wire-Free or Wired | White | AVD2001

Arlo Essential Video Doorbell Wire-Free |HD Video, 180° View, Night Vision, 2-Way Audio | 6-Months Battery Life | Direct to Wi-Fi, No Hub Needed | Wire-Free or Wired | White | AVD2001

List Price: $199.99

New From: $199.99in Stock