There is a growing market surrounding digital voice assistants, and it is being led by the four biggest tech companies in the world. Apple (Siri), Microsoft (Cortana), Google (Assistant), and Amazon (Alexa) have been competing for supremacy for years. In a very rare move, Microsoft and Amazon have announced a unique new partnership.

The two companies have been working behind closed doors on a Cortana – Alexa integration. More specifically, the two rival virtual assistants can now communicate with each other. Due to be announced today, the development would let users speak to Cortana using Alexa, and vice versa.

It is potentially significant for Microsoft. Earlier this month, former executive and Cortana developer Qi Lu claimed Microsoft had lost the virtual assistant battle to Alexa. He argued while Microsoft (and indeed Apple and to a lesser extent Google) focused on mobile, Amazon understood the need for a dedicated device.

Lu believes the true power of a voice assistant is in the home, the office, and the car. Amazon’s Echo range of smart speakers highlighted how an assistant can help manage the connected home. It is a move Google followed, and more recently Apple and Microsoft also jumped on board.

In terms of the Microsoft and Amazon collaboration, it marks a rare moment where two leading companies cooperate on nascent technology. All these companies are pouring huge resources into development of voice controlled assistants. Being smarter and more powerful is the eventual goal.

In its announcement today, Microsoft explained how the integration will work:

“Alexa as a guest on Cortana

With Alexa as a guest on Cortana, Cortana users will now have another way of making their lives easier with a great shopping experience. Say you are at work, and you receive a text from your partner saying, “We’re running low on diapers.” In the future, on your Windows 10 PC, iPhone or Android phone, you could simply say, “Hey Cortana, open Alexa,” and ask Alexa to order diapers using your preferred payment method for your Amazon account.

Cortana as a guest on Alexa

With Cortana as a guest on Alexa, Alexa users will have access to some of Cortana’s most useful productivity capabilities that help people stay organized and on top of what’s important to them. What if you’re making breakfast in the morning and need to know if you have enough time to drop off the dry-cleaning before work? On your Alexa device, you can say, “Alexa, open Cortana,” and ask when your first meeting is. If you won’t have enough time, simply ask Alexa to open Cortana again and set a reminder for the end of your workday to drop off the clothes.”

Amazon CEO Jeff Bezos and his Microsoft counterpart, Satya Nadella, believe separating the assistants could ultimately slow down development. They believe Cortana has abilities Alexa lacks, and vice versa. Each could benefit and grow from the other.

In an interview last week, Bezos hinted at this collaboration by offering praise to Cortana. “I want them to have access to as many of those AIs as possible,” Bezos said, before giving Microsoft’s assistant as an example.

Bezos points out that Cortana has better integration with Outlook because Microsoft develops both services. The company can integrate Cortana more deeply into its own services, such as the wider Office suite. Amazon could attempt to match integration with Alexa, but could never equal Microsoft’s access.

It is a theory that could also be applied to Google’s ecosystem, and to some extent Apple’s. Bezos and Nadella believe collaboration is the way forward. In Amazon’s case, Alexa will now have access to the same responses as Cortana, offering deeper integration.

Collaboration

Bezos made the first moves at Microsoft’s annual CEO Summit in Seattle. Nadella quickly warmed to the idea and development began on how the integration would work. Speaking to The Seattle Times, Nadella says assistants can collaborate in a similar way to web browsers:

“The personality and expertise of each one will be such that if they interoperated, the user will get more out of it,” he says. “That resonated for me and for him, and then that’s what led to the teams working.”

The next logical step would be to integrate Siri and Google Assistant. Bezos says no contact has been made but he would be open to the idea.

“I’d welcome it,” he said.

“Hopefully, they’ll be inspired by it,” Nadella said. “At least that would be my hope.”