How to Block Fake Teams Calls in Microsoft 365

Would you answer a Teams call that looked like it was from “Microsoft Support”?

Many people would and that’s exactly what threat actors are counting on.

As Microsoft Teams has become central to business communication, it’s also becoming a new tool for cybercriminals. Attackers are now using free or trial Teams accounts to impersonate trusted organizations such as Microsoft, internal IT staff, or vendors to initiate fraudulent calls and gain access to company resources.

The Risk: External Trial and Free Teams Accounts

Microsoft Teams allows communication between different organizations by default, including M365 Trial accounts and unmanaged (“free”) Teams accounts tied to personal Outlook.com emails. While this makes collaboration easy, it also means malicious actors can initiate unsolicited calls directly into your Teams environment.

The Fix: Update Your Teams External Communication Settings

Microsoft 365 provides a few simple settings to prevent these unsolicited calls while maintaining legitimate collaboration. By reviewing your External access configuration in the Teams Admin Center, you can control who can contact your users.

• Admin Portal: Teams Admin Center > Users > External access

• Recommended configuration:

This adjustment means free Teams users can still join meetings you create, but they can’t initiate random calls or chats to your staff.

Stay Secure and Connected

Teams is an incredible collaboration tool, but it’s becoming a favorite vector for social engineering. A few small configuration changes can make a big difference in preventing impersonation attempts and protecting your organization.

If you’re unsure whether your Microsoft 365 settings are protecting your business, book a call with Elevate Cyber Solutions. We’ll review your Teams and M365 security configurations to help keep your business secure and communication safe.