It's BS. I changed my user agent to Chrome and it worked just fine.

It is BS, but when I tried that, I had other things not working, like sharing my screen. So it is BS, but not merely for looking at the user agent of the browser, but for the software development incapability or unwillingness on the side of MS. (Edit: While basically every other voice chat / video chat web app works fine on FF, so basically everyone but MS and Slack has solved this problem years ago. Go figure.)

GoToMeeting also refuses to work in Firefox.

Yes, I have the exact same situation, and had to resort to uBlock Origin's element zapper because of how annoying that popup is. Of course it's an alphabet soup of minified CSS classes, so I assume it'll break the next time they update the UI.

I know! Eight zillion designer-hours in to one of the most-used applications of all time, and yet the "you can join now" popup blocks the "join" button.

Firefox is an unsupported browser - Teams works fine on Edge.

> Teams works fine for me on Edge.

"If you don't want to install our app, you can just install our browser."

Except it works when you supply the Edge user agent on Firefox, unlike Google services which are much harder to work around.

Define "it works".

For me, with this method, text chat works a bit (often forgets chat history on reload). Notifications get dropped all the time. No video conferencing at all. Sometimes I have to discuss with colleagues, why my teams acts weird.