How do I choose a PSTN connectivity option for Teams Phone?

Choosing a PSTN connectivity option means deciding how Teams Phone reaches the regular telephone network, because the phone license by itself only handles calls between people inside your organization.[1][2] To dial and receive normal landline and mobile numbers, each user needs a Teams Phone license plus a separate connection to the public switched telephone network, or PSTN, and Microsoft supports four ways to supply that connection: a Microsoft Calling Plan, Operator Connect, Teams Phone Mobile, and Direct Routing.[1] The four models differ mainly in who acts as your carrier and how much of the underlying connection you manage, so the choice is less about call quality and more about coverage, control, and who holds the support contract.[1]

The license and the connection are separate decisions

A Teams Phone license turns on the calling and PBX features, and every one of the four options still requires that license on each user.[1] What changes between the options is the source of the phone numbers and the route to the outside network, which means you can settle the licensing question first and treat the PSTN option as a second, independent decision.[1][2]

You are not locked into one model

One tenant can run more than one connectivity type at the same time, and you can add or change them over time in any order.[1] That matters for the decision because a company with offices in several countries rarely finds a single option that covers everyone, so the realistic outcome is often a mix, for example a Calling Plan where it is sold and Direct Routing where it is not.[1]

A Microsoft Calling Plan fits when having Microsoft sell you the dial tone in your country is acceptable and you would rather not manage a carrier relationship at all.[1][2] With this option Microsoft is your PSTN carrier, supplying the phone numbers, the calling minutes, United States emergency screening, and support under a 99.999% reliability service level agreement, and there is no hardware or session border controller to run.[1][2]

You buy a Teams Phone license first, then add a Calling Plan license per user, choosing a Domestic, International, or Pay-As-You-Go plan based on how much your users call out.[2] Users in the same country on the same plan share a pool of minutes, so a Domestic plan suits steady in-country calling while Pay-As-You-Go tends to fit lighter or occasional callers.[2] The deciding factor is usually availability, because Calling Plans are sold in a limited set of countries, and the country is set by the location of each user's Microsoft 365 license rather than your billing address.[2][7] A company with users outside that list has to cover those users with one of the other three options.[1][7]

Operator Connect fits when you want a specific third-party carrier to run the connection for you, either your current provider or a new one from Microsoft's directory, without buying or managing any voice hardware.[1][3] The operator supplies the PSTN access, phone numbers, emergency screening option, support, and the service level agreement, and you enable them and assign their numbers from the Teams admin center.[1][3] The operator manages the session border controllers, so you avoid running that infrastructure yourself, and deployment is generally quick because the carrier has already certified the connection into Teams.[3]

This tends to suit an organization whose preferred carrier participates in the program, or one that needs managed calling in a country where Microsoft's own Calling Plan is not sold.[1][3] Coverage is the thing to check first, since each operator serves its own list of countries, so the practical question is whether a participating operator covers the places your people work.[3][8] Users need a Teams Phone license and must be in TeamsOnly mode, though the whole organization does not have to be.[3]

Teams Phone Mobile fits staff who want a single company mobile number that works as both their cell number and their Teams number, so one line rings on the native mobile dialer and inside Teams at the same time.[1][4] It relies on a certified mobile operator that has completed the integration with Microsoft, and the piece you administer is the mobile SIM, which can be an eSIM.[1][4] The operator provides the PSTN access, numbers, support, and service level agreement, much like Operator Connect but built around a mobile subscription rather than a landline service.[1][4]

This is aimed at mobile-first roles such as field and sales teams, where carrying one number across the desk phone, the Teams app, and the handset removes the split between a work line and a personal mobile.[4] Availability again decides it, because your mobile provider has to take part in the Teams Phone Mobile program, so confirming that with the carrier comes before any planning.[1][4] In practice it is the least adopted of the four models, so it is worth treating as a fit for specific mobile workers rather than a default for the whole company.[8]

Direct Routing fits when you need to keep a specific carrier, operate in a country where the managed options are not available, or connect Teams to existing phone equipment, and you accept running more infrastructure in return for that flexibility.[1][5] It connects almost any PSTN trunk to Teams through a certified session border controller that you, an integrator, or a Direct-Routing-as-a-Service provider procures and manages, and it is the one model that works in any country.[1][5] It also interoperates with third-party PBXs and analog devices such as overhead paging, which is often the reason a business with legacy gear chooses it.[1][5]

The cost of that flexibility is responsibility, since the SBC brings certificate management, DNS and firewall configuration, call-routing policies in Teams, and the last-mile circuit into the SBC, so it asks more of your IT team or partner than the other options do.[1][5] Direct Routing is also the only model that can keep local PSTN calls working through a Survivable Branch Appliance if the connection to the Microsoft cloud is interrupted, which matters for sites that cannot tolerate losing the phones during an outage.[1][11] Where the extra control is not needed, a managed option usually reaches a working state faster.[9][11]

Four practical questions settle most of the decision: where your users are, whether you want to keep a current carrier, how much infrastructure you can run, and what your emergency-calling and continuity requirements are.[1] Working through them in order usually points to one or two options per group of users rather than a single company-wide answer.[1]

Are the managed options sold where your users are?

Start with geography, because Microsoft Calling Plans are sold only in a limited set of countries, and each Operator Connect or Teams Phone Mobile carrier covers its own list.[2][3][7] If a managed option covers all your locations, it removes the most infrastructure from your plate; if it does not, Direct Routing is the model that reaches any country.[1][5]

Do you need to keep your existing carrier or numbers?

If a current carrier contract or a specific operator relationship has to stay in place, that narrows the field quickly.[1] Operator Connect keeps a preferred carrier when that carrier is in the program, while Direct Routing keeps any carrier at the cost of running the connection yourself.[1][3][5] A Microsoft Calling Plan replaces the carrier entirely, so it only fits when you are content to move that role to Microsoft.[2]

How much telephony infrastructure do you want to run?

The options line up on a scale from fully managed to fully self-run.[9][10] Calling Plan and Operator Connect leave no SBC for you to manage, Teams Phone Mobile adds only the mobile SIM, and Direct Routing puts the session border controller and its upkeep on you or a partner.[1] Matching that scale to the telephony skills you actually have in-house, or the partner you can call on, keeps the deployment realistic.[9][10]

What are your emergency-calling and uptime needs?

Emergency calling and outage tolerance differ by option and can be decisive in regulated or safety-sensitive settings.[1] A Microsoft Calling Plan includes United States emergency screening and a Teams-admin-managed registered address, the operator-led options offer emergency screening as an option they manage, and Direct Routing supports dynamic emergency calling but needs extra configuration and does not support a registered address.[1] If a site must keep calling during a cloud interruption, only Direct Routing with a Survivable Branch Appliance provides that local fallback.[1][11]

Yes, one tenant can use several PSTN connectivity types at once, and mixing them is a normal design for anything beyond a single-country setup.[1] Microsoft's own guidance describes starting with Calling Plans and Shared Calling for everyone, then layering more specific options by persona, such as Teams Phone Mobile for mobile workers, Operator Connect for knowledge workers, and Direct Routing for people in regions the other options do not cover.[1]

You can also mix options for a single user. A user assigned a Calling Plan or an Operator Connect number can still route some calls through Direct Routing, which is commonly set up so that calls to a third-party PBX stay on the enterprise network instead of going out to the PSTN.[5] Enterprises with users in many countries often end up here by necessity, running one managed option where a carrier has strong coverage and Direct Routing where it does not, or where local integration and compliance rules require an on-premises connection.[8][10]

Each option carries limits that are easier to plan for than to discover later, and most of them touch cost, coverage, or who carries the support burden.[1][6]

The phone license is not the whole bill

A Teams Phone license on its own cannot call the outside world, so the real cost includes the PSTN option on top of it.[1][2] Microsoft lists Teams Phone Standard at $10.00 per user per month, while a bundle that adds a domestic Calling Plan runs about $17.00 and a domestic-and-international bundle about $34.00, and Operator Connect or Direct Routing carry their own carrier and, for Direct Routing, SBC costs.[6] Budgeting only for the phone license understates what a working deployment costs.[6]

Coverage and carrier participation vary

Microsoft Calling Plan availability is limited by country, and both Operator Connect and Teams Phone Mobile depend on a specific carrier taking part and covering your locations, so coverage can be the constraint that removes an option before cost ever enters the picture.[2][3][7] Confirming availability early for every country you operate in avoids designing around an option you cannot actually buy.[7][8]

Direct Routing shifts work onto you

The flexibility of Direct Routing comes with the ongoing upkeep of the session border controller, its certificates, and its routing configuration, whether your team runs it or a Direct-Routing-as-a-Service provider does.[1][5] That upkeep is manageable, but it is a standing responsibility rather than a one-time setup, so it belongs in the decision rather than as an afterthought.[5][9]

Continuity and emergency calling need attention

Because Teams calls travel over the internet, a managed cloud option depends on the connection to Microsoft staying up, and only Direct Routing with a Survivable Branch Appliance keeps local calling during a cloud interruption.[1][11] Emergency-calling setup also differs by option, so the registered-address and dynamic-location details are worth confirming per site, especially for people who move between locations.[1]

Choosing a PSTN option is a separate decision from buying the Teams Phone license, and a few common mix-ups are worth clearing up before you commit.[1]

It is not the same as the Teams Phone license

The Teams Phone license enables the calling features but does not connect you to the outside phone network on its own.[1][2] The PSTN option is the second piece that supplies the numbers and the route to landlines and mobiles.[1]

A Microsoft Calling Plan is not the only way

A Microsoft Calling Plan is one of the four options, not a requirement.[1] You can run Teams Phone entirely on Operator Connect, Teams Phone Mobile, or Direct Routing and never buy a Microsoft Calling Plan, which matters most in countries where Calling Plans are not sold.[1][2]

It is not a permanent, one-time commitment

The choice is not locked in, since a tenant can add, change, or combine connectivity types over time and in any order.[1] An option chosen for one group of users does not bind the rest of the organization, so the decision can grow with the deployment.[1]

Operator Connect and Direct Routing are not a quality ranking

Neither managed nor self-run connectivity is inherently better calling; they differ in who runs the connection and how much control you keep, not in call quality.[9][10] The right pick depends on coverage, existing carrier relationships, and the infrastructure you want to own, which is why the same feature can be the deciding factor for one organization and irrelevant to another.[1][9]