Microsoft and Cisco interoperability does exist in unified communications. But, for team collaboration, Microsoft Teams integration with Cisco Spark adds another wrinkle.
Many of the companies we work with at Nemertes Research are both Cisco and Microsoft shops for unified communications. Typically, they have large investments in Cisco phone and video conferencing systems, while they also use Microsoft Skype for Business — either on premises or via Office 365 — for instant messaging and presence. Often, these companies also use both Cisco WebEx and Skype for Business meetings for web conferencing.