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TEAMS.TC.5012 - Call Forwarding to Phone

Description​

This test checks if call forwarding to external phone numbers (PSTN) is appropriately configured.

Policy Statement​

Contoso's company policy requires call forwarding to PSTN to be carefully reviewed due to toll fraud risks.

Why This Matters​

Call forwarding to PSTN can enable toll fraud, where attackers:

  • Compromise user accounts
  • Forward calls to premium-rate numbers
  • Generate significant charges (potentially thousands of dollars)
  • Exploit your organization's calling plan

This is one of the most common and expensive security risks in Teams calling.

How to Fix​

For most organizations, disabling this feature for all users except specific roles is the best approach:

Set-CsTeamsCallingPolicy -Identity Global -AllowCallForwardingToPhone $false

Create Exception Policies​

If some users legitimately need this feature:

  1. Keep Global policy restrictive (disabled)
  2. Create a custom policy for executive users:
New-CsTeamsCallingPolicy -Identity "ExecutivesCalling" -AllowCallForwardingToPhone $true
Grant-CsTeamsCallingPolicy -Identity "user@contoso.com" -PolicyName "ExecutivesCalling"

Implement Monitoring​

If you must enable this feature:

  • Set up alerts for unusual calling patterns
  • Monitor call detail records regularly
  • Implement spending caps with your carrier
  • Review bills frequently for anomalies

Check Current Setting​

Get-CsTeamsCallingPolicy | Where-Object { $_.Identity -eq "Global" } | Select-Object Identity, AllowCallForwardingToPhone

Learn More​