Plan for Teams Phone PSTN connectivity
A Private Branch Exchange (PBX) is a phone system within a business. Microsoft Teams Phone enables call control and Private Branch Exchange (PBX) capabilities in Microsoft 365 with Microsoft Teams.
Calls between two users in your organization are handled within Microsoft Teams and never go to the Public Switched Telephone Network (PSTN), also called a Voice-over-IP (VoIP) call. This also applies to multiparty calls between users in your organization, irrespective if they are in the same or different geographical areas, removing long-distance costs on these internal calls.
To connect Teams Phone to the PSTN, you can choose one or more of the following options for your users:
Teams Phone with Calling Plan: An all-in-the-cloud solution with Microsoft as your PSTN carrier.
Teams Phone with Operator Connect: If you want to work with an operator that is part of the Microsoft Operator Connect Program, they can bring PSTN calling to Teams.
Teams Phone with Direct Routing: Use Direct Routing to connect your on-premises environment or your chosen carrier to Teams.
Teams Phone Mobile: Allows a user’s SIM-enabled phone number to also act as their Teams phone number across both their mobile service and desk lines.
Teams Phone Shared Calling: Shared Calling simplifies phone number management for users that don't use the PSTN often, by sharing a single number with an Auto Attendant that routes incoming and outgoing PSTN calls. Shared Calling also reduces costs for your organization because you don't need a dedicated phone number for every user.
Teams Phone with Calling Plans
Teams Phone with Calling Plans is Microsoft's all-in-the-cloud solution that provides Private Branch Exchange (PBX) functionality and calls to the Public Switched Telephone Network (PSTN), as shown in the following diagram. With this solution, Microsoft is your PSTN carrier.
Teams Phone with Calling Plan might be the right solution for you if you can answer yes to the following questions:
Is Microsoft Calling Plan available in your country/region?
Would you prefer to have a single vendor for your Teams Phone and PSTN solution?
With Calling Plans:
You get Microsoft Teams Phone with added Domestic or International Calling Plans that enable calling phones around the world (depending on the level of service being licensed).
You don't require deployment or maintenance of an on-premises deployment—because Calling Plan operates out of Microsoft 365 or Office 365.
Choose to pay a monthly fee for a Calling Plan, or choose a Pay-As-You-Go Calling Plan for cost-effective billing.
Teams Phone with Operator Connect
Operator Connect is another option for providing Public Switched Telephone Network (PSTN) connectivity for Teams Phone. Operator Connect might be the right solution for your organization if:
Microsoft Calling Plan isn't available in your geographic location.
Your preferred operator is a participant in the Microsoft Operator Connect Program.
You want to find a new operator to enable calling in Teams.
Operator Connect has many benefits to organizations looking to provide PSTN connectivity to their users, especially if you want to keep your existing operator relationship. The operator provides a cloud service, manages the infrastructure and provides close support for fast, easy, and reliable deployment.
Teams Phone with your own PSTN carrier with Direct Routing
Your phone system might be more complex, and you can't answer yes to any of the questions for other Teams Phone PSTN connectivity options. For example, you might have offices in locations where Calling Plans or Operator Connect isn't available. Or you might need a combination solution that supports a complex, multi-national deployment, with different requirements for different geographic locations. In this case, the best solution might be Direct Routing, as outlined in the following diagram.
If you answer yes to the following questions, then Teams Phone with Direct Routing is the right solution for you:
You want to use Teams with Teams Phone.
You must retain your current PSTN carrier and they aren't an Operator Connect partner
You must interoperate with third-party PBXs and/or equipment, such as overhead pagers, analog devices, and so on.
With Direct Routing:
You connect your own supported Session Border Controller (SBC) to Teams Phone without the need for additional on-premises software.
You can use virtually any telephone carrier with Teams Phone.
You can choose to configure and manage this option, or it can be configured and managed by your carrier or partner (ask if your carrier or partner provides this option).
You can configure interoperability between your telephony equipment—such as a third-party PBX and analog devices—and Teams Phone.
Note
This option requires an uninterrupted connection to Microsoft 365.
Teams Phone Mobile
Teams Phone Mobile is another option for providing Public Switched Telephone Network (PSTN) connectivity with Microsoft Teams Phone. With Teams Phone Mobile, a user’s SIM-enabled phone number is also their Teams phone number. Users can use a single phone number in Microsoft Teams across both their mobile service and desk lines and seamlessly transition between networks and devices.
Teams Phone Mobile might be the right solution for your organization if:
You want to use a primary company-owned, SIM-enabled mobile number for Teams Phone as a single-number solution.
Your preferred operator is a participant in the Microsoft Teams Phone Mobile program and provides service in the countries/regions you require.
You want to find a new operator to enable calling in Teams.
Teams Phone Shared Calling
Shared Calling is recommended for users who do not heavily use the Public Switched Telephone Network (PSTN). It simplifies phone number management and reduces costs by using the phone number of a resource account associated with an Auto attendant for inbound and outbound PSTN calls.
You must create or reuse an existing resource account and assign a Teams Calling Plan service number, Operator Connect number, or Direct Routing number to the resource account to be used for inbound and outbound calling.
Teams Phone with a combination of PSTN connectivity options
You might consider a combination of PSTN connectivity options for Teams Phone. This is common in large environments. Any combination of PSTN connectivity options can be used.
For example, you might choose Teams Phone Mobile for your sales and field organizations who are mobile-first users, operator connect for users in countries/regions where it's supported by your preferred operator and Direct Routing in countries/regions where there's no Operator Connect coverage, or you need to interconnect with an existing PBX.