The only reason it exists is to keep companies trapped in the MS ecosystem. They do this with all kinds of things. For instance at my work it's required for all engineers to get Azure certified due to a deal we have with MS. They don't care about their product. They don't care about their users. Hell they don't even care about their employees. It's just B2b == money, all day every day
Microsoft Teams has a completely different technical base than Skype for Business. Other platform, other language, other tech stack, other APIs, other protocols, other features. The one that just was a reskinned something was Skype for Business, formerly known as Lync, formerly known as Office Communicator, formerly known as Windows Messenger, formerly known as Exchange Conferencing, ...
What was the name of that thing before they gave it the skypeful makeover and added a bunch of useless annoying features? It was actually pretty good back then. Every redesign since then it's been getting worse and worse.
Oh, I don't recognize that name. I ve only been using MST for a year now at a new job. Since I am a contractor for another company, I still use self hosted Rocket.Chat instance, with Jitsi integration so we can also do calls.
How recently did calling become supported? About a month ago I was still unable to even log in using Firefox unless I used a user agent switcher, and even then only text-based messaging worked.