https://arstechnica.com/gadgets/2018/09/skype-support-coming-to-alexa-later-this-year/

Later this year you'll be able to say "Alexa, call Mom on Skype" and have Amazon's digital assistant do the right thing with Microsoft's messaging network.

Microsoft and Amazon have been working to integrate their technology. Earlier in the year, Cortana and Alexa gained the ability to talk to each other (albeit with some limitations), and the Skype integration is another sign of cooperation between the two companies.