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8x8 Support

8x8 Phone App for Microsoft Teams


8x8 Phone App for Microsoft Teams enables Teams users to place and receive public switched telephone network (PSTN) calls from within Microsoft Teams without additional licensing requirements or software.

Online documentation for both Administrators and Users is linked below.


Applies To

  • 8x8 Work
  • Microsoft Teams
  • 8x8 Voice for Microsoft Teams
  • 8x8 Phone App for Microsoft Teams


The new Phone App uses Microsoft-supported calling technologies, increasing stability and reliability. The interface has also been improved while maintaining the feature set of the previous version, providing users a positive experience moving to this new version.

Features include:

  • Dial any outbound number, including extensions
  • Search and manage contacts
  • View and filter call history
  • Manage active calls
  • Answer incoming calls in Teams via a desktop, web, or mobile
  • User presence accurately reflects call status to other users in Teams
  • No per user Teams Phone license required
  • Native PSTN calling in Microsoft Teams with no cross-launch to software outside of Teams or desktop plugins

Requirements, Limitations, & Important Usage Info


  • At least one 8x8 Voice for Microsoft Teams user must be active on the 8x8 service for Phone App users to be enabled.
  • Each Phone App user must be assigned an 8x8 X Series license. All licenses are supported except for Lobby and XT licenses.
  • An MS Teams Integration license in 8x8 Admin Console user profiles must be enabled for each Phone App user.
  • Phone App users cannot have either a Microsoft Phone System license or Calling Plan assigned to them.
  • Setup requires action by a Microsoft Global Administrator, and by an 8x8 admin with at least Users permission assigned.
  • Large Tenant Mode is required to be enabled in the 8x8 Voice for Teams admin portal. This means that both Phone App users and Voice for Teams users must be added to separate Azure AD security groups.

Phone App Additional Requirement

Phone App requires that an unallocated Microsoft Teams Phone Resource Account license be available on your Microsoft tenant. The setup process will create an otherwise unlicensed user on your Microsoft service and will assign the Phone Resource Account license to it.

If you don't already have such a license, it can usually be acquired from Microsoft at no cost. Please see this Microsoft article for information regarding Teams Phone Resource Account licenses.


  • For Phone App users, the following features are not supported due to Microsoft licensing and Phone App limitations:
    • Click-to-call from Microsoft Teams > Calls app > Contacts
    • Warm transfer available for internal transfers, only. External (PSTN) transfers must be made as cold transfers.
    • Conference calls with external phone numbers
    • Promote call to meeting with external participants is not supported. Promotion to meeting is only supported with other internal Teams users.
  • In Teams for Web, 8x8 Ring Groups are supported, but only when the Ring Pattern is set to Sequential (Cyclic Repetitive). This limitation is not present when using the Teams client.



Phone App supports Consult and transfer to another Phone App user on the same tenant.

Please see these articles for important information about call transfers:

Important Usage Info

  • Outbound Call Behavior
    • By design, initiating an outbound call will result in the Teams user first receiving an inbound call. That inbound call must be answered to complete a connection to the called phone number. This is expected behavior.
    • The native Calls app in the Teams app bar can be used for contacting other Teams users on the same Microsoft service. However, external (Non-Teams) phone number dialing is prohibited there, and will fail. This is because Phone App users do not have a Microsoft Phone System license or Calling Plan applied to them (a requirement for Phone App users).
  • Call Transfers
    • Call transfers to external numbers must take place within the Phone App interface, not within the Teams native active-call window.
    • As stated above, warm transfers for external calls are not supported in the Phone App. Only for internal transfers via the native Teams call window.
  • Call History
    • The 8x8 Phone App has its own call history, which displays accurate inbound, outbound, and missed-call information.
    • Note that call history in the native Teams Activity app in the Teams app bar will also be displayed, but all calls in that app will be marked as Inbound.
    • Contents of the 8x8 Phone App Contact list are polled only from Microsoft. Contacts are not polled from 8x8 due to Microsoft API limitations.
    • The Phone App's Contacts list is drawn from the following. Contacts will only be displayed if phone numbers are assigned in the Office/Business or Mobile phone fields:
      • Licensed users on the same Microsoft service.
      • Contacts created by users in their Microsoft Teams client.
      • Contacts listed in the user's Microsoft Outlook 365 (online).
    • Microsoft Exchange GAL (Global Address List) is supported in the Phone App. As stated above, these contacts will only be displayed in the Phone App Contacts > My Organization list, and only when a phone number is assigned in a user's Office/Business or Mobile phone field.
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