It cannot integrate with or handle existing VoIP services, receive or answer phone calls, handle land and cellular switches and terminals, and it cannot route or transfer calls (audio or video) automatically. It doesn’t handle automated away time messages or rerouting, auto-replys to chat, it cannot serve users external of the organization. And those are only the few things I use daily, sure there must be many more things that Skype can do an Teams just doesn’t because it’s a slack and zoom hybrid. It just doesn’t fit the role Skype has in my org and it’s why we continue to run both together until the very second the Skype servers are finally shut down.