I think Teams is actually just leveraging the Skype backend. I looked at some of the network calls happening in their web app, and some requests are referencing

I think Teams is actually just leveraging the Skype backend. I looked at some of the network calls happening in their web app, and some requests are referencing skype (e.g. https://amer.ng.msg.teams.microsoft.com/v1/users/ME/conversations/dd%3A<uniqueId>%40thread.skype/properties?name=consumptionhorizon https://amer.ng.msg.teams.microsoft.com/v1/users/ME/conversa...)