"Once you open Cortana, all voice data goes to Microsoft and not Amazon, and once you open Alexa, all voice data goes to Amazon and not Microsoft", said Amazon spokeswoman Dawn Brun in a statement past year.
That isn't exactly the most seamless of integrations-it adds one more step between activating the virtual assistant and having it do what you want-but it will make Cortana and Alexa available on more devices. You can now access both Alexa and Cortana on each of them.
Alexa, which does everything from play music to buy items from Amazon on Echo speakers and other Alexa-enabled devices, will be able to summon Cortana to read emails or check calendar appointments from Microsoft Outlook.
That's the premise behind a cooperative effort from Amazon and Microsoft that lets Alexa users cue up Cortana on their Echo speakers. The roll out begins today and it will be available to all users in the United States by next week.
After all, the advent of Alexa for Business means that Microsoft likely needs Amazon more than the other way around. On a compatible Windows 10 PC or a Harman Kardon Invoke smart speaker, you can say "Hey Cortana, open Alexa", and you'll be able to shop on Amazon or control some smart appliances.
The companies first announced plans to have their personal assistants work together a year ago, saying the integration would launch by the end of 2017.
The tie-up between Cortana and Alexa will be available in the US only at first, and both companies are requesting that users provide them with feedback that can be used to improve the feature.
The integration was given a short demo in May in Seattle at Microsoft's Build conference.
A Microsoft spokesperson told ZDNet that this integration is now limited. More details will be released in the coming days, the spokesperson said.
Today, Amazon and Microsoft are officially unveiling the Alexa/Cortana integration. "Engineers will use feedback from the public preview to deepen the collaboration between Cortana and Alexa".