Microsoft launched its Slack competitor, Microsoft Teams, just over a year ago. At launch, the software giant only unveiled paid subscriptions for its chat service, with no free or freemium tiers for businesses to upgrade from. It looks like that’s about to change, though. Petri reports that the latest test versions of Microsoft Teams include multiple references to a freemium tier, with options to “upgrade to paid version.”

It appears that Microsoft is testing this functionality out, before rolling it out publicly. It’s not clear how the free tier of Microsoft Teams will work, but if it’s similar to Slack then it will probably be limited to a certain number of people on a server until paid features are required. Slack has had the benefit of reaching emerging startups, small businesses, and other businesses that don’t rely on Windows or Office, and its freemium model has helped it grow and thrive in the chat business. If Microsoft does launch a free version of Teams then Slack will have even more reason to be nervous of Microsoft’s service.

Subscriptions are becoming increasingly important to Microsoft as it continues to push cloud-based software and services. Speaking at the Morgan Stanley TMT conference on Monday, Microsoft CEO Satya Nadella hinted that Office 365 growth could be better than the old days of Windows client and server. “The growth opportunity for what is Office 365 is a lot bigger than anything we’ve achieved, even with our high penetration in the client-server world” said Nadella.