Microsoft Teams PSTN Calling Guide

Microsoft Teams is now the default collaboration hub for most large organizations, handling meetings, messaging, and file sharing in one place. But when it comes to making actual phone calls to clients, vendors, or anyone outside your organization, Teams alone doesn't cut it. That's where PSTN calling comes in, and it confuses more IT teams than it should.

This guide covers two things: what PSTN calling is and how to enable it in Microsoft Teams. You'll find three connectivity options compared side by side, a step-by-step Direct Routing setup walkthrough using PBX.IM, and answers to the questions that come up every time.

If you're an IT admin evaluating how to add phone capabilities to Teams, or already deploying and getting stuck, this guide covers both sides in one place.

TL;DR

• PSTN is the global phone network that connects every landline and mobile; Teams can't reach it without additional setup
• Microsoft Calling Plans are the simplest option but cover only ~36 countries and cost more at scale
• Operator Connect works if your carrier is already a Microsoft partner, with no SBC required on your end
• Direct Routing through a provider like PBX.IM gives you 150+ country coverage, lower costs, and full control over routing and features

What Is PSTN, and How Does It Relate to Microsoft Teams?

PSTN stands for Public Switched Telephone Network. It's the traditional global phone network, the one that connects every landline, mobile, and business phone system on the planet. Before VoIP existed, all voice calls traveled through it.

By default, Microsoft Teams handles internal calls between your organization's users over the internet. Those are free and require no additional setup. What Teams cannot do out of the box is call a regular phone number: a client's mobile, a supplier's office line, a government agency's main number. For that, you need to connect Teams to the PSTN.

Making that connection requires two things: a Teams Phone license and a PSTN connectivity method. That's it. The rest of this guide is just those two things in detail.

What Is PSTN Calling?

PSTN calling is the ability to make and receive calls to and from regular phone numbers (any landline or mobile, anywhere in the world) directly from Microsoft Teams.

Internal Teams calls run over VoIP and are included with your Microsoft 365 license. External PSTN calls are different. They require dedicated infrastructure and per-user licensing to route calls through the public phone network.

To make PSTN calls from Teams, you need:

• A Teams Phone license per user (standalone or bundled with Microsoft 365 E5)
• A PSTN connectivity method: Microsoft Calling Plans, Operator Connect with a carrier that is a Microsoft partner, or Direct Routing through a provider like PBX.IM
• A phone number, new or ported from your current provider
• An E.164-formatted dial plan (optional but strongly recommended for consistent international dialing)

Once those are in place, your users make and receive calls from the Teams client exactly as they would from any business phone.

How to Enable PSTN Calling in Microsoft Teams: 4 Options

There are four ways to connect Microsoft Teams to the PSTN. The right one depends on where you operate, what infrastructure you already have, and how much control you want over routing and cost.

Microsoft Calling Plans: Easiest setup, but limited to 36 countries

With Microsoft Calling Plans, Microsoft acts as both your Teams vendor and your phone carrier. You buy minutes and numbers directly from Microsoft, assign them to users in the Teams Admin Center, and you're done. No SBC, no third-party carrier, no extra configuration.

Pros: Fastest to deploy. Billing is consolidated inside your Microsoft 365 account. No telephony expertise required.

Cons: Available in approximately 36 countries, excluding Thailand, Vietnam, most of Southeast Asia, most of LATAM, and large parts of Africa and the Middle East. Pricing runs $12–$24 per user per month for domestic plans, higher for international. At scale, the cost adds up fast.

Best for: Small deployments in the US, UK, or Western Europe with no existing PBX and no international calling requirements outside Microsoft's coverage footprint.

Operator Connect: Low-effort deployment, if your carrier is a Microsoft partner

Operator Connect lets you keep your existing carrier as long as they're a Microsoft-approved Operator Connect partner. The carrier manages PSTN connectivity for you directly inside the Teams Admin Center. You select them from the list, provision numbers, and assign them to users. No SBC on your side.

Pros: Simpler than Direct Routing. You keep your carrier relationship. No SBC setup or management required on your end.

Cons: You're limited to carriers in the Operator Connect program. If your preferred carrier isn't on the list, this option isn't available to you. The participating carrier list is growing but still incomplete, particularly outside North America and Western Europe.

Best for: Mid-size businesses whose carrier is already an Operator Connect partner and who want a faster deployment than Direct Routing without switching carriers.

Direct Routing: The most flexible option. Works in any country, keeps your PBX, adds advanced features

Direct Routing connects Microsoft Teams to the PSTN through a Session Border Controller (SBC), a certified gateway that sits between Teams and your carrier's network. You bring your own carrier. That carrier can be PBX.IM.

Pros: Works in any country, regardless of Microsoft's Calling Plan availability. You can keep your existing PBX and carrier contracts. Per-minute costs are significantly lower than Microsoft Calling Plans. Full control over call routing, number management, and features.

Cons: More technical to configure than the other options, specifically the Teams-side setup. The rest of this guide walks through exactly that.

Best for: Mid-to-large businesses with an existing PBX, organizations operating in countries where Calling Plans aren't available (Thailand, Vietnam, most of LATAM, Africa, Middle East, Asia-Pacific), and anyone optimizing cost at scale.

PBX.IM is a Direct Routing provider. The Free plan covers one account at no cost, with paid tiers starting at $25/month, which means you can test the full setup before committing.

Comparison: Which PSTN connectivity option is right for you?

How to Enable PSTN Calling in Microsoft Teams with Direct Routing

Before you start, make sure you have the following:

• A Microsoft 365 tenant with users homed online
• A Teams Phone license assigned to each user who needs PSTN calling
• A PBX.IM account (sign up free at pbx.im)
• Global Admin or Teams Administrator access in Microsoft 365

PBX.IM provides a pre-configured, Microsoft-certified SBC. You handle only the Teams-side configuration below.

Step 1. Sign up for PBX.IM and get your SBC credentials

Create your PBX.IM account. Once your account is active, navigate to your Direct Routing settings inside the PBX.IM dashboard. You'll find your assigned SBC FQDN (Fully Qualified Domain Name), which will look something like sbc.pbx.im. Keep this on hand for the steps that follow.

PBX.IM manages the SBC configuration on its end, including TLS certificates and network settings. You don't need to provision hardware or configure the SBC yourself.

Step 2. Add your SBC to the Microsoft Teams Admin Center

Sign in to the Microsoft Teams Admin Center with your Global Admin or Teams Admin credentials.

1. In the left navigation, go to Voice > Direct Routing
2. On the SBCs tab, select Add
3. Enter the SBC FQDN provided by PBX.IM (e.g. sbc.pbx.im)
4. Set SIP signaling port to 5067 (confirm with PBX.IM if different)
5. Toggle SBC enabled to On
6. Leave media bypass settings as recommended by PBX.IM
7. Select Save

Once saved, the SBC status will show as Active within a few minutes if connectivity is established correctly.

Step 3. Create a PSTN Usage Record

PSTN usage records define which types of calls are permitted. You'll reference this record in your voice route and routing policy.

1. In the Teams Admin Center, go to Voice > Direct Routing
2. In the upper-right corner, select Manage PSTN usage records
3. Select Add, type a name (e.g. PBX.IM International), and click Apply

Step 4. Create a Voice Route

A voice route tells Teams which SBC to use for calls matching a given number pattern.

1. Go to Voice > Direct Routing > Voice routes tab
2. Select Add
3. Enter a name (e.g. PBX.IM Route)
4. Set Dialed number pattern to .* to match all numbers, or use a more specific pattern if needed
5. Under SBCs enrolled, select Add SBCs and choose the SBC you registered in Step 2
6. Under PSTN usage records, select Add PSTN usage and choose the record you created in Step 3
7. Select Save

Step 5. Create a Voice Routing Policy and Assign it to Users

A voice routing policy links your PSTN usage record to specific users.

1. Go to Voice > Voice routing policies
2. Select Add
3. Give the policy a name (e.g. PBX.IM Direct Routing Policy)
4. Under PSTN usage records, select Add PSTN usage and choose the record from Step 3
5. Select Save

Now assign it to users:

1. Go to Users > Manage users
2. Select a user, click Policies, then Edit next to Assigned policies
3. Under Voice routing policy, select the policy you just created
4. Select Apply

Step 6. Assign a Phone Number to the User

1. Go to Users > Manage users and select the user
2. Click Edit next to General information
3. Under Phone number, enter the number provided by PBX.IM in E.164 format (e.g. +12025550100)
4. Set Phone number type to Direct Routing
5. Select Apply

The user is now fully configured for PSTN calling through PBX.IM.

How to Make Your First Call in Microsoft Teams Through PBX.IM

Once the configuration above is complete, making your first PSTN call takes about 30 seconds.

1. Open Microsoft Teams on desktop or mobile
2. Click the Calls tab in the left navigation
3. Select Dial a number or use the keypad icon
4. Enter any external phone number in full international format (e.g. +44 20 7946 0000)
5. Press Call

The call routes through PBX.IM's SBC to the PSTN. You'll see the call status update in real time inside Teams.

To test inbound calling, ask someone to dial the phone number assigned to your Teams user. The call rings directly inside the Teams client.

If your first call fails, confirm that:

• The voice routing policy is assigned to the user (Step 5)
• The phone number is in E.164 format (Step 6)
• The SBC shows as Active in the Teams Admin Center (Step 2)
• The user has a Teams Phone license assigned in Microsoft 365 Admin Center

Why Choose PBX.IM as Your Direct Routing Provider

Direct Routing only works as well as the carrier behind it. Here's what separates PBX.IM from the alternatives.

Coverage in 150+ countries, including the ones Microsoft skips

Microsoft Calling Plans cover approximately 36 countries. PBX.IM covers 150+. The difference isn't marginal. It's every market that matters for globally distributed teams: Thailand, Vietnam, the Philippines, most of LATAM, Africa, the Middle East, and across Asia-Pacific. You get local numbers in any of those markets, managed through a single Teams interface.

Pricing that starts at zero and caps at $50

Microsoft Calling Plans start at $13/user/month for domestic and climb to $34/user/month for international. PBX.IM runs Free / Essential at $25 / Core at $40 / Advanced at $50, with a 25% discount on annual plans. That's a meaningful difference every month, coming in at under half what Microsoft charges for equivalent functionality.

The omnichannel feature set Microsoft doesn't offer

Teams Phone covers basic calling. PBX.IM layers on the capabilities Teams is missing: AI Auto Dialer, Auto Attendant and IVR, call recording to email, caller ID management, business SMS, and WhatsApp Business messaging. If you've been stitching those together with separate tools, PBX.IM consolidates them under one platform and one bill.

A Microsoft-certified SBC, managed for you

SBCs, FQDNs, TLS certificates, PowerShell cmdlets: the infrastructure side of Direct Routing is where most deployments stall. PBX.IM ships the SBC pre-configured and manages it on its end. You handle the five Teams-side steps above. That's it. You do the steps above. We handle the rest.

Number porting in three steps, not three months

Whether you're migrating from Microsoft Calling Plans, a legacy PBX, or another Direct Routing provider, PBX.IM handles number porting through a self-serve portal with a three-step process. Your customers dial the same numbers they always have. Nothing on their end changes.

Real humans, on real shifts

PBX.IM's support team works actual shifts with direct contact, not a ticket queue with a two-day SLA. That sounds like standard marketing copy until the night of your first outage, when it isn't.

Microsoft Teams PSTN Calling: FAQs

Can I use my existing phone numbers with Teams?

Yes. PBX.IM supports number porting, which means you can transfer your current business numbers to the PBX.IM platform and assign them to Teams users. The porting process runs through a self-serve portal and typically completes within a few business days depending on your current carrier. Your numbers stay the same. Only the carrier changes.

Is Direct Routing better than Microsoft Calling Plans?

For most mid-to-large organizations, yes. Microsoft Calling Plans are simpler to set up but cost significantly more at scale, cover only about 36 countries, and don't support keeping your existing PBX or carrier. Direct Routing with PBX.IM gives you 150+ country coverage, lower per-minute costs, and a full feature set that Calling Plans don't include. The main trade-off is a slightly more involved initial configuration, which this guide walks you through.

Which countries don't have Microsoft Calling Plans?

Microsoft Calling Plans are unavailable in most of Southeast Asia (including Thailand and Vietnam), most of Latin America, most of Africa, and most of the Middle East. The current list covers approximately 36 countries, concentrated in North America, Western Europe, and a handful of Asia-Pacific markets. For the full and current list, check Microsoft's Calling Plans availability page.

Can I keep my PBX and use Teams for calling?

Yes, that's one of the core use cases for Direct Routing. PBX.IM connects Microsoft Teams to your existing PBX infrastructure, so you don't have to rip and replace anything. Internal calls can still route through your PBX while external PSTN calls flow through Teams. You can also migrate gradually, moving departments or locations to Teams calling over time while the rest of the organization continues on the PBX.

Can I send SMS or WhatsApp messages from Microsoft Teams?

Not through native Teams functionality. Teams doesn't support outbound SMS or WhatsApp messaging to external numbers. PBX.IM covers both. With PBX.IM's WhatsApp Business integration and business SMS capabilities, your team can send and receive messages through the same platform that handles your PSTN calls, without switching apps or managing separate tools.

How long does it take to set up Direct Routing with PBX.IM?

For most IT admins following this guide, the Teams-side configuration (Steps 2–6) takes under an hour. Signing up for PBX.IM and getting your SBC credentials takes a few minutes. Number porting (if you're moving existing numbers) adds a few business days depending on your current carrier. If you want guided setup, the PBX.IM team offers a Direct Routing walkthrough that covers the full configuration in a single session.