We also use Slack. We use a lot of Google solutions as our corporate mail is Gmail. I’ve also used Skype (as a corporate account) and Zoom. That was in previous companies. Zoom was okay, however, as far as my computer was concerned, it was 100% CPU usage, so I don't like it so much. We had some issues sometimes sharing when I had several screens on my desk. Sometimes when you don't share a good screen, it's very difficult to come back. With Skype, it has been a long time since I have used it. However, I recall it was very basic. It doesn't have the same capabilities as seen in Google Hangouts.
