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Common reasons for blocking SPAM calls

  • Reduces unwanted distractions and interruptions during work.
  • Protects against security risks such as malware and phishing.
  • Improves productivity by allowing employees to focus on tasks.
  • Simple and effective way to improve efficiency and security of the organization.

There are several options available to block SPAM calls in Microsoft Teams:

  1. Microsoft Teams Tenant level Call Blocking Rules: Set with PowerShell using Regex expressions. This allows you to set up call blocking rules to block specific numbers or number ranges. You can also block entire countries, regions etc.
  2. Microsoft Teams Direct Routing: This feature allows you to connect your existing PSTN (Public Switched Telephone Network) infrastructure to Microsoft Teams, allowing you to use your existing (Carrier provided) call blocking and filtering solutions.
  3. Third-Party Call Control: Microsoft Teams also supports integration with third-party call control solutions, such as those provided by companies like Ribbon Communications and AudioCodes. These solutions allow you to use advanced call blocking and filtering features.
  4. Teams Client Side Call blocking: Done by the user from Call History or Contacts.

The Teams Call Blocker Tool focuses on the first option above, simply put, the PowerShell is wrapped in a GUI to simplify the management.

Blocking Numbers with PowerShell makes use of the CsInboundBlockedNumberPattern command.

CsInboundBlockedNumberPattern is a PowerShell cmdlet used in Microsoft Teams to block incoming calls from specific phone numbers or patterns of numbers. The calls that are blocked are determined by the number patterns specified in the cmdlet.

For example, if you run the command New-CsInboundBlockedNumberPattern -Identity "+1234" -Pattern "+1234*", it will block all incoming calls from phone numbers that start with +1234.

Similarly, you can block specific phone numbers or patterns of numbers by specifying the appropriate number pattern. The cmdlet can be used to block a specific phone number, a range of numbers, or a wildcard pattern.

Please note that this cmdlet will only block the inbound calls on Teams SIP and PSTN numbers and will not affect the Direct Routing numbers.

Also, this cmdlet works at the tenant level and it will block the calls for all users in the tenant if it’s executed by a tenant admin.

NOTE: To enable tenant-level blocked numbers, run the command Set-CsTenantFederationConfiguration -BlockedNumbersEnabled $true