Liza Bazilevici creates content at PBX.IM focused on cloud telephony, VoIP systems, and contact center solutions. She makes complex topics easier to navigate, offering practical insights that help IT teams and business leaders understand and choose the right communication tools.
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Discover what Microsoft Teams Direct Routing is and why it is worth implementing it with PBX.IM. Elevate your business communication to the next level!
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.
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.
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:
Once those are in place, your users make and receive calls from the Teams client exactly as they would from any business phone.
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.
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 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 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.
Before you start, make sure you have the following:
PBX.IM provides a pre-configured, Microsoft-certified SBC. You handle only the Teams-side configuration below.
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.
Sign in to the Microsoft Teams Admin Center with your Global Admin or Teams Admin credentials.
Once saved, the SBC status will show as Active within a few minutes if connectivity is established correctly.
PSTN usage records define which types of calls are permitted. You'll reference this record in your voice route and routing policy.
A voice route tells Teams which SBC to use for calls matching a given number pattern.
A voice routing policy links your PSTN usage record to specific users.
Now assign it to users:
The user is now fully configured for PSTN calling through PBX.IM.
Once the configuration above is complete, making your first PSTN call takes about 30 seconds.
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:
Direct Routing only works as well as the carrier behind it. Here's what separates PBX.IM from the alternatives.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Set up Direct Routing in under an hour. No hardware, no complexity, no Microsoft Calling Plan pricing.
