Microsoft and Amazon made their voice assistants into friends. Here's how that relationship works.

Amazon.com and Microsoft have officially set up the friendship between their two voice assistants, Alexa and Cortana, a year after announcing the partnership to expand the reach and abilities of the competing assistants. But how does this relationship of rivals work? To talk to one assistant through the other, customers have to say either "Cortana, open Alexa" or "Alexa, open Cortana." From there, people can talk to the other assistant as usual. What they don't get is access to each others' data, according to statements from both companies Wednesday.