[Note]: - You need a PC and a mobile phone with the Messenger app installed on it and connected to the internet. [Affected versions]: - Beta 63.0b3 - Nightly 64.0a1 [Affected platforms]: - Windows 10 x64 - macOS 10.13 - Ubuntu 16.04 x64 [Steps to reproduce]: 1. Log into Facebook. 2. Click on one of the friends from the list on the right side of the site. 3. Instead of messaging them try to call them. [Expected result]: - The call goes through. [Actual result]: - The call doesn't go through. There is nothing displayed on the mobile screen, only after you close the call. Then a notification is displayed. [Regression range]: - last good build: 2018-07-31 - first bad build: 2018-08-01 - Mozregression concluded that bug Bug 1476600(Stop reusing mids from stopped transceivers) might have caused this. [Additional notes]: - If the call is made from the mobile, then the call goes through without any issue.

ni? Bryon based on the mozregression result

So I just tried this, I don't see any failures in the JS log, so I don't think facebook is doing anything like hard-coding mids in the answer. It may simply be that they don't like the new format for the mids.

It looks like Facebook creates an offer (on Firefox) with one audio m-section, calls SLD, and then closes the PC. This is almost certainly just a case where the thing on the other end didn't like the SDP we created, which would be a facebook bug. Someone should give them a heads-up.

Notified Facebook. Their frontend team is looking at it.

I don't know if this information is useful or not, but I would like to mention the fact that this issue is not reproducing on Chrome. If the call is made from Chrome on a mobile device, the call goes through without any issues.

Nils, any news from Facebook frontend team? Thanks

Latest status is that Facebook is actively working on a fix on their end.

If I understand the last email from Facebook correctly this issue got fixed on their end. Oana, could you please verify that it is fixed?

I can still reproduce the issue using the latest Nightly 64.0a1 on Windows 10 x64. It's still has the same behaviour.

I reached out to FB asking when the fix is expected to available to all users (assuming that they are maybe doing a staged roll out by default).

Facebook is internally testing the fix right now.

The appears to be working for me. Tested in Firefox 64 for MacOS, voice & video calling an iPhone with the app.

I also was able to place a call from Fx 64 to Messenger on iOS. Looks like we now had several people verifying that it work again.

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:64.0) Gecko/20100101 Firefox/64.0 20181019100103 We have verified the mentioned behavior is not reproducible anymore. The facebook audio/video call is going through either the latest Nightly or Beta builds on a desktop to iOS or Android mobile device. Verified platforms as follow: Ubuntu 18.04 x64 to iOS/Android Windows 10 x64 to iOS/Android MacOS 10.14 to iOS/Android