Microsoft recently announced via an email blast that Skype for Business is slated to be retired on July 31, 2021. After that date, Skype for Business will no longer be accessible or supported.
Microsoft is encouraging businesses and organizations to begin using the new Microsoft Teams product that now comes with Office 365. Microsoft Teams offers group chat, online meetings, web conferencing, and collaboration using Office 365 apps.
You can find additional information about Microsoft Teams at: