(1623340) Firefox compatiblity with Microsoft Teams and Teams for friends and family

User agent overrides

Spun off from https://bugzilla.mozilla.org/show_bug.cgi?id=1623340#c5

A fix would be for Firefox to spoof its own user-agent string, so it represents itself as whatever the latest version of Edge is.

The functionality works, but Microsoft is blocking it through user-agent sniffing. …

Firefox could spoof the user-agent when any Microsoft site is visited (based on a list of primary domains, perhaps). …

… In addition to the HTTP User-Agent, changes may also be needed to data in the window.navigator object to circumvent this.

Earlier this week I began testing this Edge string (the latest):

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.102 Safari/537.36 Edg/85.0.564.51

– overriding these two URLs:

https://teams.microsoft.com/
https://statics.teams.cdn.office.net/

– specified in Custom UserAgent String added to Firefox 80.0.1 on FreeBSD-CURRENT.

Results

Meet in a group context: a moment after apparently beginning the meeting – the camera image appears as it should – the image disappears, leaving an alert:

Sorry, we couldn’t connect you.

– and two buttons:

  • Retry
  • Dismiss

– retries do not succeed.

Unwanted effects of the override include breakage of OneNote:

Sorry, we ran into a problem.

Your feedback helps Microsoft improve OneNote. Give feedback to Microsoft

  • Restart

– restarts lead to the same problem.

Without the override for the two domains

OneNote works:

With the override for https://teams.microsoft.com/ alone

OneNote breaks.

With the override for https://statics.teams.cdn.office.net/ alone

OneNote works.

Meet in a group context results in an explicit alert, before the AV dialogue:

Use the app or a supported browser

Related

Hi,
any news on this issue?
Thank you

On the Mozilla side: none that I can see.

On the Microsoft side:

Off-topic: Zoom

From @andreip at https://microsoftteams.uservoice.com/forums/555103-public/suggestions/36946039-calls-support-in-firefox-mozilla:

This is why I use Zoom. Zoom just works on the web in Firefox.

I should not encourage use of Zoom.

Recently I was invited to two meetings – online rallies – both of which included an invitation to join from the browser, both of which failed when the invitation was accepted. Poor user experience.

The first meeting – using Microsoft Edge on Windows 10 1909 – was particularly troublesome, because the failure directed me to download Zoom from Microsoft’s Store, in a managed environment where it was impossible to do so. I was forced to go elsewhere and use a different computer.

A screenshot of the second failed meeting – Google Chrome on FreeBSD-CURRENT:

– less troublesome than the first, in that download of the installer for Zoom succeeded (without requiring Microsoft’s Store) but still, a poor user experience.

I was misled (by Zoom) into believing that Zoom would work in web browsers, but it didn’t, and the discoveries caused me to miss the beginnings of both meetings.

From https://github.com/webcompat/web-bugs/issues/25070#issuecomment-743936967

… I was able to record even a call in zoom. It works well for me.

I don’t doubt it :slight_smile: but I should not recommend use of a service that misrepresents itself.

Nightclub organiser:

Come to our club tonight! No footwear restrictions. Just register in advance.

Doorman:

Your name’s on the list. Come in! No footwear restrictions. Now turn around. Go away. You can’t come in wearing trainers. Go to that shoe shop – over there – register and sign in over there to get a pair of shoes that suit our non-advertised restrictions.

Shoe shop:

Welcome! Thank you for signing in; we require this before selling shoes. Now turn around. Go away. We’re not allowed to sell shoes to you.

teams.live.com (Teams for friends and family)

I lazily use this override:

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.102 Safari/537.36 Edg/85.0.564.51

It’s enough for text chat but (as expected) not enough for video.

Postscript

Re: https://github.com/phts/firefox-web-skype/issues/9 I now (more lazily) use web.skype.com for Firefox

Any news on this? This is what I get when I spoof with Microsoft Edge:

ff_spoofing_edge

What are the technologies used by Microsoft Teams that Firefox doesn’t support? Why we can’t just implement the support on our own after spoofing?

From https://github.com/webcompat/web-bugs/issues/25070#issuecomment-751324990:

… MS Teams so far only supported Chrome’s proprietary Plan B for SDP used in WebRTC. Teams switched to the standard way (aka Unified Plan) of doing things, but are facing now issues from designing everything around Chrome initially. …