Because of the Coronavirus, Microsoft offers its collaboration application Teams for free. Currently there are three variants:

There is already a free teams version available since 2018. This version is slightly limited in its functions (e.g. less storage space, no phone calls to landlines, etc.).

Since March 2020, Microsoft offers the following two additional deals:

  • The Office 365 Business Essentials subscription six months free of charge if you commit to it for one year.
  • The fully functional trial version of Office 365 E1 for six months free of charge. This offer is available through your Microsoft Account Manager or your Microsoft CSP Partner.

An overview of the different Office 365 plans can be found here:
https://docs.microsoft.com/en-us/office365/servicedescriptions/office-365-platform-service-description/office-365-plan-options

Microsofts commitment to customers during COVID-19
https://news.microsoft.com/en-my/2020/03/17/our-commitment-to-customers-during-covid-19/