You can. However, despite Slack offering a free communication tool to businesses looking for a chat solution, you do have to purchase a premium plan (from $6.67 per month) if you want to host video conferences. Once you've paid, you'll be able to add integrations with Microsoft Teams, Zoom, RingCentral and more. With the free plan however, you will only be able to partake in 1-to-1 video calls (of dubious quality). Simply put, Slack is only the right choice if you're looking for a written communication tool primarily, and not a video conferencing app.