Tom Talks Microsoft Teams and Microsoft 365 news and opinions

Slack CEO forecasts 50 million active Microsoft Teams users in the next six months and 100 million within the next year


Interesting comments from Stewart Butterfield, Chairman, Chief Executive Officer and Co-Founder at Slack on their quarter 3 earnings call:

I want to acknowledge the escalation in competitive narratives. Microsoft has announced that there are now 20 million people using Teams, around 10% of their Office365 user base.


When they first announced the shutdown of Skype for Business, we expected this. All the way back in 2015, Microsoft announced that Lync had 100 million active users. We have no reason to assume that any of those were lost when Lync was rebranded as Skype for Business. The product still drove end users’ desktop VOIP phones and conference rooms.


Now that Skype for Business users are being force-migrated to Teams, it’s reasonable to expect more of the same. Unless they hit a snag, we’d expect them to announce 50 million in the next six months and then 100 million within the next year.

I still think those forecasts sound high in the timelines, but we’ll see over the coming year.

The Lync 2015 number is interesting. In 2015, based on my experience, most Lync users were actually on-premises Server users, not Office 365.

He goes on to position Slack as substantially different to Microsoft Teams, and that Office 365 customers are still choosing Slack in some cases.

  • Slack CEO Stewart Butterfield said that they now have more than 50 customers paying at least $1 million a year, up from 30 in the same quarter a year earlier
  • Butterfield said almost 70% of those customers also use Office 365
  • Now up to over 105,000 Paid Customers, up 30% year-over-year

Slack Stats from their earnings call:


Microsoft is increasingly targeting Slack, now having specific documentation on how to Migrate from Slack to Microsoft Teams

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About the author

Tom Arbuthnot

A Microsoft MVP and Microsoft Certified Master, Tom Arbuthnot is Principal Solutions Architect at Microsoft Collaboration specialists Modality Systems.

Tom stays up to date with industry developments and shares news and his opinions on his blog, Microsoft Teams Podcast and email list. He is a regular speaker at events around the world.

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Tom Talks Microsoft Teams and Microsoft 365 news and opinions