Google has quickly expanded its Duplex restaurant reservation service to more users, who can now use the Assistant to call up and book a table on their behalf.

The piece of artificial intelligence was first demonstrated by Google in the summer, and in October was rolled out to a small number of trusted beta testers. But now, some Google Pixel users not part of the initial test have found the system works for them too.

Read More:

• Google's human-sounding AI launches to early testers
• Will Google Duplex replace call centers?
• Hello, AI speaking: Google Duplex will identify itself as non-human

Using an astonishingly accurate sounding voice, Duplex can call up a restaurant of your choosing, then act like a real personal assistant, requesting a table for a certain number of people and at a specific time.

The system works by you telling the assistant the details of the booking in advance - by speaking to your phone, naturally. The assistant then makes the call on your behalf, and will try again if it can't get through the first time.

You can also ask the assistant to try a couple of different times, in case your ideal time is unavailable. The conversation is carried out entirely by the assistant, with no input from you.

This is the first step of what Google describes as a "slow rollout" of the service to owners of Google Pixel phones. For now, the system can only manage calls in English, and is only available in a handful of US cities, including New York, Atlanta, Phoenix and San Francisco.

Google is not yet giving members of the press access to the system, but as luck would have it, a couple of Pixel review phones owned by VentureBeat were included in the initial rollout. The site was able to test Duplex by making a restaurant reservation, which you can see in the YouTube video below.

As with the first demonstrations of Duplex, the voice sounds uncannily like a human, only with a slightly unnatural pause before making each utterance. Aside from that, the conversation flows seamlessly.

Duplex begins the call by saying "Hi, I'm making a reservation for a client I' calling from Google so the call may be recorded. Can I book a table for tomorrow please?"

The conversation between Google Assistant and the restaurant worker then flows naturally, complete with realistic-sounding 'ums' and 'erms' made by the AI.

The technology on display here is deeply impressive, but we wonder if it is really all that beneficial. As VentureBeat documents, setting up the call takes a fair amount of time as you tell the Assistant where and when you'd like the table, and for how many people. We're left wondering if it is quicker and easier to just pick up the phone ourselves.

That said, if the restaurant is busy and usually requires several calls to get through - or if you need to make the call while in a meeting or away from your phone, then setting things up with the Assistant in advance could certainly be helpful.