Thanks to @frossie, we now have a meeting arranged through the LSST project-provided BlueJeans teleconference system.
BlueJeans supports browser-based audio and video conferencing, including screen-sharing, and also has native apps for various platforms, including Mac OS X, Android, and iOS. BlueJeans supports dialing in from classical “room system” videoconference devices (e.g., Polycoms).
It is possible to connect by telephone to BlueJeans meetings, but the resulting audio quality is usually worse than for VOIP connections. (We have had particularly bad experiences with dialing in to BlueJeans meetings from mobile phones via the telephone number. Use an app if you are on a mobile!)
Confirming that I was able to login and view the message. Note for Chrome users - bluejeans does not work on Chrome (at least on Linux but I believe on other systems too) – so you will need to use firefox.