How to enabling Dial by Extension in Auto Attendant

Enabling Dial by Extension for Your Organization

To enable Dial by Extension for users in your organization, ensure that the appropriate phone attributes are defined in Active Directory or Microsoft Entra ID.

Phone Attributes

Use these attributes to specify a user’s extension:

• TelephoneNumber (AD) or BusinessPhone (Microsoft Entra ID)
• Mobile (AD and Microsoft Entra ID)
• HomePhone (AD) – legacy field
• OtherTelephone (AD) – legacy field

Required Formats for Extensions

When entering extensions in user phone fields, use these formats:

1. Semicolon format: +<phone number>;ext=<extension>
2. ‘x’ format: +<phone number>x<extension>
3. Extension-only: x<extension>

PowerShell Examples

Update mobile numbers with extensions using PowerShell:

Semicolon Format

Update-MgUser -UserId 'usern@domain.com' -MobilePhone '15555555678;ext=5678'

‘x’ Format

Update-MgUser -UserId 'usern@domain.com' -MobilePhone '+15555555678x5678'

Extension-Only

Update-MgUser -UserId 'usern@domain.com' -MobilePhone 'x5678'

Alternative Configuration Methods

Extensions can also be set through:

• Microsoft 365 admin center
• Microsoft Entra admin center