A comprehensive guide to Microsoft Teams SIP trunking

For many organizations, Microsoft Teams is the go-to hub for workplace communication, collaboration, and productivity. From chat and video calls to document sharing and project management, Teams ensures employees stay connected across offices, countries, and time zones.

However, despite its benefits, Microsoft Teams doesn’t natively allow you to make and receive traditional phone calls outside of the Teams environment. That’s where SIP trunking with Microsoft Teams comes in.

SIP (Session Initiation Protocol) trunking enables businesses to connect Microsoft Teams to the public switched telephone network (PSTN). This means Teams users can seamlessly make and receive calls to and from external, PSTN, or fixed-line phone numbers.

In this article, we’ll explore the business benefits of Microsoft Teams SIP trunking, how it works, and how to implement it with best practices.

The benefits of a Microsoft Teams calling package

Choosing how to enable external calling in Microsoft Teams comes down to three packages. Here’s how the benefits stack up for typical business needs:

Microsoft calling plans: The simplest start, with limited reach

• Fastest to get going because service is provided by Microsoft and managed in the Teams Admin Center
• Standard voice routing and Microsoft Teams-only integrations, which keep things straightforward but less flexible
• Availability is restricted to a small set of countries, so multi-region rollouts can be constrained

Operator Connect (Sipcom HALO): Streamlined management in Microsoft Teams

• Connectivity provided by Sipcom via trusted cross-connects into Microsoft, delivering an enterprise-grade voice network with no additional on-prem equipment
• Managed in the Microsoft 365 Teams Admin Center with additional control via Sipcom’s portal, simplifying number and service management
• Standard routing and Microsoft Teams-only app integrations offer ease of use rather than deep customization
• Coverage depends on participating carriers in each country, so reach is broader than calling plans but still governed by carrier availability

Direct Routing (Sipcom HALO): Maximum flexibility and global scale

• External carrier services connect to Microsoft Teams via a hosted or on-premises SBC, giving you full control of call-routing policies
• Fully configurable voice routing plus support for hybrid environments, connecting legacy PBXs, contact centers, and analog devices on the same network
• Voice application integrations are fully supported by Sipcom, enabling bespoke workflows beyond Microsoft Teams-only APIs
• Global coverage without limitation via Sipcom’s hosted, fully managed SBCs – ideal for multinational deployments

Ultimately, choose Microsoft Calling Plans if you want the quickest, simplest way to enable Microsoft Teams calling in a limited set of countries. Opt for Operator Connect (via Sipcom HALO) when you prefer admin-friendly management with carrier-grade connectivity. And when you need maximum flexibility, select Direct Routing (via Sipcom HALO) for hybrid support, advanced routing control, broader integrations, and truly global coverage.

How to set up SIP trunking with Microsoft Teams

While enabling external calling via Direct Routing or Sipcom HALO Bring-Your-Own-Trunk (BYOT) can feel technical, you can simplify the process with our four-step approach:

Step 1: Assess your current communication setup

Before making changes, take a moment to carefully review your existing infrastructure:

• Do you already use a PBX (Private Branch Exchange)?
• Do you have an SBC (Session Border Controller) in place?
• What’s your current call volume and bandwidth capacity?

Understanding your starting point ensures you’ll choose the right SIP configuration and provider for your organization.

Step 2: Choose a SIP trunking provider

When sourcing a provider for SIP trunking with Microsoft Teams, it’s vital to choose one that’s built for Microsoft Teams. Here are the key criteria to ask:

Compatibility: Look for Microsoft-certified options such as Direct Routing, plus provider capabilities like Sipcom HALO BYOT that interoperate cleanly with Microsoft Teams. Not every provider offers this depth of alignment.

Coverage: If your business operates globally, ensure the provider offers local phone numbers in the regions you need.

Reliability: Ask about uptime guarantees and backup systems to keep your phones online.

Call quality: A strong provider will deliver crisp, clear calls without lag or distortion.

Support and pricing: Look for transparent costs and responsive support teams, so there are no surprises.

This is where Sipcom can add real value. As a trusted Microsoft Teams partner, Sipcom offers SIP trunking services designed specifically to optimize Teams deployments, ensuring compatibility, scalability, and long-term reliability.

Step 3: Configure SIP trunking with Microsoft Teams

At the core of this step is Direct Routing – the process of connecting Microsoft Teams to the PSTN via a certified SBC. The SBC acts as the secure bridge between Teams and the phone network outside your organization.

To configure SIP trunking with Microsoft Teams, you’ll need to:

1. Connect your SBC (hosted by your provider or self-managed)
2. Link Teams to the SBC using Microsoft-approved methods
3. Ensure you have the required Microsoft Phone System license, which is included in Microsoft 365 E5 or as an add-on

Many organizations also choose Sipcom HALO BYOT to maximize flexibility. It lets you integrate your own devices and services, such as PBXs, contact centers, and third-party SIP providers, on a temporary or permanent basis, helping you protect existing investments while moving to Microsoft Teams.

Delivered on Sipcom’s scalable, reliable, and secure HALO platform, BYOT provides a robust route for calls to pass to/from third-party services and devices into the wider HALO environment. In short, BYOT pairs with Direct Routing to give you full control of routing and the freedom to mix legacy and modern endpoints without compromise.

Step 4: Test and optimize the setup

Once the configuration is complete, you’ll need to:

1. Test inbound and outbound calls across different scenarios (local, long-distance, international).
2. Check call quality, failover performance, and redundancy systems.
3. Collect user feedback to ensure adoption is smooth.
4. Monitor analytics to spot performance bottlenecks.

This is also the stage to fine-tune call routing rules, emergency services configurations, and security settings.

Best practices for optimizing SIP trunking with Microsoft Teams

To get the most out of SIP trunking with Microsoft Teams, keep these best practices in mind:

Ensure sufficient bandwidth: As each call consumes bandwidth, it’s vital to make sure your internet connection can support expected call volumes alongside other business traffic.

Standardize devices and Teams clients: Reduce compatibility issues by ensuring all employees use updated Teams apps and supported devices.

Leverage SBC-as-a-Service: Offload the complexity of managing and securing an SBC by letting a provider like Sipcom host it for you.

Monitor performance: Use Teams analytics and provider dashboards to track call quality, utilization, and adoption.

Secure your setup: Configure SBCs with encryption, role-based permissions, and external-facing safeguards.

Rely on expert partners: Providers like Sipcom offer ongoing consulting and support to optimize SIP trunking and Sipcom HALO BYOT/Direct Routing setups.

By following these practices, businesses can maximize call quality, ensure reliability, and provide employees with a seamless communication experience.

Integrate SIP trunking with your Microsoft Teams deployment today

With the right support, you can transform Teams into a fully unified communications platform – combining chat, video, and external voice calls in one place. Simply contact our team and we can help you get started. Or, if you’re a partner looking to guide customers on their UC journey, partner with us – we’d be glad to help.