Alexa and Cortana are now BFFs - you can use Alexa-enabled devices to talk to Cortana and vice versa. This feature was unveiled by Microsoft and Amazon at Microsoft's BUILD developer conference, but was limited to beta testers. It is now available to a wider audience as a public preview. Note that this is available only in the US for now. Here's how it works. Say you have an Amazon Echo. You can say "Alexa, open Cortana" and then ask her about your schedule, send an email and anything else the assistant can do. You can do multiple commands without having to say "Open Cortana" before each...
Source: https://www.gsmarena.com/alexa_and_cortana_can_now_trade_places_alexa_on_windows_10_cortana_on_echo-news-32782.php