Dial-Tone Options in Microsoft Teams

July 11, 2018 Ella Wright

Microsoft Teams Direct Routing was recently announced for general availability for all Office 365 customers. Direct Routing allows organizations to use their existing telecommunications provider or PBX equipment to enable employees to make and receive telephone calls in Microsoft Teams.  Organizations now have two different scenarios to choose from that will enable dial-tone calling for Microsoft Teams.  Direct Routing is not available for Skype for Business Online.

The first scenario allows organizations to connect their own Session Border Controller to almost any telephony trunk or PBX equipment and to Office 365 Microsoft Teams with Phone System. This adds flexibility for organizations to use Microsoft Phone system by allowing them to configure inter-operability between existing on-premises equipment and Microsoft Teams.  Organizations typically choose Direct Routing when:

  1. Microsoft Calling Plans are not available
  2. The organization requires connection to third party solutions such as call centers or analog devices such as paging systems or elevators
  3. The organization has an existing contract with a telecommunications provider

The following includes the list of requirements to implement Direct Routing with Microsoft Teams.

  • Session Border Controller which has a public IP address.  The SBC can use NAT and it must be assigned a Fully Qualified Domain Name (FQDN).  The FQDN must be published externally.  In addition, the SBC must have a public certificate installed which contains the FQDN in the subject, common name, or subject alternate name fields. Direct Routing does support wildcard certificates.
  • Office 365 tenant
  • Users must be homed in Office 365.  It is not possible to enable Voice in teams for a user homed in an on-premises deployment of Skype for Business or Lync Server.
  • One or more domains added to the Office 365 tenant.  The default O365 domain *.onmicrosoft.com cannot be used
  • Users must have the following Office 365 Licenses assigned:
    • Skype for Business Online (Plan 2)
    • Microsoft Phone System
    • Microsoft Teams
    • Microsoft Audio Conferencing

The second scenario allows organization to use Microsoft Teams with Phone System without having on-premises equipment. This Partner Hosted offering enables organizations to completely move into a cloud solution.

Below are a few of the Telecommunications providers which offer Direct Routing to Microsoft Teams and links to their offerings.


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