The Microsoft Teams Connector solutions can utilize contact information in various contexts (see below). The contact information is retrieved from Teams, Azure Active Directory (also referred to as AD or Entra), and/or Outlook. 

Sources for Contact Information

Azure Active Directory Contacts:

• Scope: Azure Active Directory Contacts are typically used in the context of Azure Active Directory (Azure AD), Microsoft's cloud-based identity and access management service. These contacts are often related to identity management and access control within an organization's network and cloud resources.
• Management: Azure Active Directory Contacts are available to enterprise administrators. They can be synchronized across various Microsoft services (such as a local Active Directory). They are available through the Microsoft Graph API.
  
  The Azure Active Directory Contacts can be managed at this contacts administration page.
   

• The Azure Active Directory Contacts of an organization are viewable by each member from their Outlook's Directory > All Users folder.
  
   

Outlook Contacts:

• Scope: Outlook Contacts are primarily used for email communication and scheduling within the Outlook application, part of the Microsoft Office suite. Each member creates contacts, including email addresses, phone numbers, physical addresses, and other personal details useful for communication and organization.
• Management: These contacts are accessible within Outlook and through the Microsoft Graph API.
  
  A member of an organization can manage its Outlook Contacts in Outlook's Your Contacts folder.
   

Teams Contacts:

• Scope: Teams Contacts are used within the Microsoft Teams platform.  These contacts are focused on facilitating chat, calls, meetings, and collaboration within Teams.
• Management:  Teams Contacts are only available to Teams users through Teams. Teams users can add, remove, or organize contacts in Teams based on their collaboration needs. Microsoft Teams Contacts include both individuals and groups. 
  There is no API available for Microsoft Teams Contacts. Consequently, they are not accessible to Microsoft Teams Connector solutions.
  
   

How Contacts are Used

Teams Dial Pad—When using the Teams dial pad, transferring a call to an external PSTN number or one of the user's contacts is possible. In this context, the available contacts will include those Teams Contacts or Azure Active Directory Contacts.  

Azure Active Directory Contacts are generally available to all enterprise users, while Teams contacts are restricted to the Teams user. Note that Azure Active Directory Contacts are not used for inbound calls and will not show as the caller name.

It is a common practice to create an Azure Active Directory Contact for external PBX extensions such that these extensions are available and associated with the associated PBX user name when transferring a call from the Teams dial pad.

Calling App—When using the Calling App, it is possible to call or transfer a call to a PBX extension, an external PSTN number, or one of the user's contacts. In this context, the available contacts will include Teams contacts, those included in Azure AD, or Outlook contacts. Azure Active Directory Contacts are generally available to all users within the enterprise, while Teams Contacts and Outlook Contacts are restricted to the respective Teams or Outlook user.

It is a common practice to create a contact for external PBX extensions such that these extensions are available and associated with the associated PBX user name when dialling or transferring a call from the Calling App.

SMS Connector - When using the SMS Connector Smart Composer, it is possible to send an SMS to an external SMS-enabled number, or a contact with a mobile number.  Also, when receiving an SMS, the SMS Connector will attempt to match the sender's number with a contact number and a matching mobile number.  In this context, the available contacts will include those included in Azure AD or Outlook.  Azure Active Directory Contacts are generally available to all users within the enterprise, while Outlook contacts are restricted to the Outlook user.

Teams Contacts are not used in the SMS Connector.

Tip: Syncing Contacts

It is a common and useful practice for an organization to create an Azure Active Directory Contact for external PBX extensions such that these extensions are available and associated with the associated PBX user name when transferring a call from the Teams dial pad.

If your PBX platform is UnitedCloud, you may check the Contact-Sync Application.