Behind the scenes, Teams connects to the global PSTN, the same network that has supported business calling for decades. The difference is where control and management live. Call routing, voicemail, call queues, and policies are no longer tied to physical PBX hardware. They are managed through cloud services, making it easier to support remote workers, scale users up or down, and standardize calling across locations.
This guide explains how PSTN calling Microsoft Teams works in practice, the different ways organizations can connect Teams to the PSTN, and why many enterprises are replacing legacy PBX systems with Teams as their primary voice platform.
What is Microsoft Teams PSTN Calling?
Microsoft Teams PSTN calling is the capability that connects Teams to the Public Switched Telephone Network (PSTN), allowing users to place and receive external calls to landlines and mobile phones directly from Teams.
Without PSTN calling, Teams only supports internal calls between users on the platform. With PSTN calling Microsoft Teams becomes a full business phone system: users get phone numbers, voicemail, call routing, and the ability to dial any external number.
Under the hood, this functionality is delivered through Teams Phone, Microsoft’s cloud-based voice service. Teams handles the user experience, while Microsoft or a certified carrier handles the PSTN connectivity that bridges Teams to the outside world.
For buyers evaluating enterprise voice, the key point is simple: Microsoft Teams PSTN calling replaces desk phones, on-prem PBXs, and separate voice platforms with one system employees already use every day.
How PSTN Calling works in Microsoft Teams
At a high level, PSTN calling Microsoft Teams follows a straightforward call flow, even though the infrastructure behind it is complex.
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A user places a call from the Teams app on a laptop, mobile device, or desk phone.
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That call is processed by the Microsoft Teams cloud, which acts as the call control layer.
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From there, the call is routed through Microsoft’s voice services or an approved carrier connection and delivered to the PSTN, reaching the external phone number.
Incoming calls work the same way in reverse.
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A customer dials a business number
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The call enters the PSTN
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It’s handed off to Microsoft’s cloud
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And then rings the Teams user or call queue.
From an IT perspective, Microsoft Teams PSTN combines three core components:
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Teams as the user interface
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A cloud PBX through the Teams Phone System
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PSTN connectivity provided by Microsoft or a carrier
This architecture is why Teams can scale globally, support remote users without VPNs, and eliminate the need for on-prem phone hardware.
There isn’t a single way to enable Microsoft Teams PSTN calling. Microsoft supports multiple models, each designed for different enterprise requirements. Choosing the right one depends on geography, carrier strategy, compliance needs, and existing voice investments.
Microsoft Calling Plans
Microsoft Calling Plans are the most straightforward option for PSTN Calling Microsoft Teams. Microsoft acts as the phone carrier and provides phone numbers, domestic calling, and international calling add-ons.
Who it’s for? This model works well for smaller deployments or organizations that want minimal complexity. There’s no carrier negotiation, no session border controllers to manage, and no third-party contracts. Everything is bundled through Microsoft.
The tradeoff is flexibility. Calling Plans are not available in every country, and large enterprises may find the pricing or routing options limiting.
Operator Connect
Operator Connect sits between Calling Plans and full custom routing. With this option, organizations use approved telecom providers that integrate directly with Microsoft’s cloud.
Who it’s for? For companies that want Microsoft Teams PSTN connectivity but prefer a familiar carrier, Operator Connect offers a clean approach. Carriers manage the PSTN infrastructure, while Microsoft manages Teams. Provisioning and monitoring are handled inside the Teams admin center, not through custom hardware.
This model is popular with multinational organizations that already have strong carrier relationships but don’t want to run their own voice infrastructure.
Direct Routing
Direct Routing is the most flexible and most complex option. It allows organizations to connect Teams to virtually any carrier using a certified Session Border Controller (SBC).
Who it’s for? With Direct Routing, PSTN calling Microsoft Teams can integrate with existing SIP trunks, legacy phone systems, or highly customized call routing environments. This is often the choice for large enterprises with contact centers, regulatory requirements, or non-standard dialing plans.
The upside is control. The downside is responsibility. IT teams or partners must deploy and manage the SBCs and ensure reliability and security.
Key benefits of Microsoft Teams PSTN Calling
Microsoft Teams PSTN calling changes how voice fits into everyday work by pulling business calling into the same system people already use to communicate and collaborate.
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Single platform for work and voice
Employees don’t switch between apps or devices. Calls, meetings, chat, and voicemail live in one place.
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Cloud-based enterprise voice
No on-prem PBX hardware. No branch phone systems. Users can work from anywhere with the same experience.
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Scales with the business
Adding users or phone numbers doesn’t require physical installs or carrier site visits.
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Integrated call management
Auto attendants, call queues, voicemail, and reporting are built into Teams.
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Foundation for AI-driven calling
Because voice runs through Microsoft’s cloud, PSTN Calling Microsoft Teams can be enhanced with transcription, analytics, and automation that legacy PBX systems can’t support.
How AI enhances Microsoft Teams PSTN Calling
One of the biggest shifts in enterprise voice is how AI now operates even when calls traverse the PSTN. Microsoft Teams PSTN calling doesn’t treat external calls as second-class. They’re part of the same intelligent platform as internal meetings. Microsoft delivers these capabilities through Microsoft Copilot, which operates across Teams, including voice workloads.
Real-time call intelligence
AI-powered call insights are available during PSTN calls, not just Teams meetings. Live transcription converts external conversations into searchable text in real time. Speaker identification separates participants, even when one party is calling from a mobile phone or landline.
Keyword detection allows compliance teams or managers to flag specific terms during regulated calls. This is especially valuable in industries like finance, healthcare, and customer support.
Call summaries and action items
After a PSTN call ends, AI can generate summaries that capture what was discussed, decisions made, and next steps. These summaries appear in Teams chat or activity feeds, tied directly to the call.
Teams Copilot for calls can also suggest follow-up tasks. For example, after a customer call, it might draft a recap message or create a to-do item based on what was said. This reduces manual note-taking and missed actions.
Compliance, recording, and analytics
AI compliance monitoring works even when calls leave the Microsoft network and enter the PSTN. Policy-based recording ensures the right calls are captured automatically.
Once recorded, AI enables search across calls. Instead of listening to hours of audio, teams can search transcripts for phrases, names, or topics. Microsoft Teams call analytics then layer usage data, quality metrics, and trends on top, giving IT and compliance teams visibility that traditional phone systems never provided.
A common question in AI overviews is whether intelligence stops at the PSTN boundary. In Microsoft Teams PSTN calling, it doesn’t. AI operates at the Teams layer, not the phone line.
Microsoft Teams PSTN vs traditional PBX systems
Enterprises evaluating Microsoft Teams PSTN often compare it to legacy PBX platforms. The difference is less about features and more about architecture.
Traditional PBX systems were designed for offices. Teams is designed for distributed work.
Teams PSTN vs PBX Comparison
For organizations still running on on-premise PBX systems, moving to Microsoft Teams PSTN calling means adopting a cloud PBX designed for how people actually work today.
Microsoft Teams PSTN calling turns Teams into a full enterprise voice platform, not an add-on. It connects everyday collaboration with the global phone network, supports multiple carrier models, and unlocks AI capabilities that legacy systems can’t match.
For enterprises evaluating voice today, the question is no longer whether Teams can replace a PBX. It’s how quickly the organization is ready to let voice live in the same cloud as everything else.
Every Teams deployment is different. Pure IP helps enterprises choose the right PSTN connectivity for Microsoft Teams based on scale, compliance needs, and existing carrier relationships. Get in touch with us for a free scoping session to get started.
