How to Set Up Teams Direct Routing in GCC High (Step-by-Step)

Government agencies and defense organizations widely use Microsoft GCC High as a secure collaboration platform for highly regulated work. However, any organization that wants to enable phone calling in Microsoft Teams will encounter a major roadblock: Microsoft Calling Plans and Operator Connect aren’t available in GCC High. For organizations needing PSTN calling, only one supported path forward exists: Direct Routing As a Service (DRaaS.

Setting up Teams Phone in GCC High doesn’t work the same way it does in the commercial Microsoft 365 cloud. GCC High operates on Azure Government, enforces U.S.-only data residency, and must comply with frameworks such as CMMC, DFARS, ITAR, and other federal requirements. These constraints fundamentally change how voice services get designed and deployed.

Enabling PSTN calling in GCC High requires a GCC High–compliant Direct Routing provider, the appropriate architecture, and configurations that align with government cloud and compliance expectations. The good news is that, when set up correctly, DRaaS operates reliably and compliantly in GCC High.

This guide walks you through the GCC High–specific, step-by-step process for enabling Microsoft Teams Direct Routing, using verified information from Atlantech Online’s Teams Calling for GCC High content and Microsoft’s official GCC High service documentation. Our goal is to help you understand the differences, the requirements, and how to move forward with confidence.

What Direct Routing Looks Like in a GCC High Environment

In a GCC High environment, enabling Microsoft Teams Phone requires DRaaS, which connects your Teams tenant to the public switched telephone network (PSTN) through a certified Session Border Controller (SBC) and a compliant voice provider. Because native PSTN Calling Plans and Operator Connect are not available in GCC High, Direct Routing is the Microsoft-mandated method for delivering phone calling and audio conferencing in these tenants.

Instead of Microsoft acting as the carrier, calls are routed through an approved third-party provider that is able to meet the technical and compliance requirements of Azure Government and GCC High.

Why This Works

DRaaS works in GCC High because it allows voice traffic to be handled by a U.S.-based, compliant carrier that aligns with the platform’s strict security and sovereignty requirements. In practice, this means:

• Call signaling and media remain within U.S.-only data pathways
• Infrastructure and operations are supported by U.S.-screened personnel
• The voice environment can support regulated workloads subject to CMMC, DFARS, and ITAR
• The architecture aligns with Microsoft’s required Phone System and Direct Routing model for GCC High

This approach gives organizations control over how voice services are delivered, while still integrating fully with Microsoft Teams inside a regulated government cloud environment.

What You’ll Do

At a high level, setting up DRaaS in GCC High involves:

1. Preparing and validating your GCC High tenant
2. Selecting a Direct Routing provider that supports GCC High and Azure Government
3. Connecting Microsoft Teams to the provider’s SBC infrastructure
4. Testing, validating, and enabling calling for users

The Step-by-Step Process

You can set up DRaaS in GCC High in four steps. The process starts with validating your tenant, then moves through provider selection, configuration, and testing before you can enable calling for users. Below, we walk you through each step in order, with GCC High–specific requirements called out along the way.

Step 1: Confirm GCC High Tenant Readiness

Confirm that your Microsoft tenant is truly operating in GCC High and is eligible to support Teams Phone through DRaaS.

Before selecting a provider or configuring any voice services, it’s important to validate that your tenant meets the baseline requirements for phone calling in a GCC High environment. This means:

• Verify that you are in a GCC High tenant, not Microsoft GCC or commercial Microsoft 365. GCC High runs on Azure Government and enforces U.S.-only data residency.
• Confirm that your licensing includes Teams Phone (Phone System) for GCC High. In this environment, Teams Phone is supported only through Direct Routing since Microsoft Calling Plans and Operator Connect are not available.
• Review your compliance requirements, such as DFARS, ITAR, or CMMC, to ensure your tenant configuration and planned voice deployment align with the regulatory obligations tied to your contracts.

Step 2: Choose a GCC High–Compliant Direct Routing Provider

Once you confirm your tenant is GCC High–ready, you’ll need to select a DRaaS provider that explicitly supports GCC High. This is a critical decision, because not all Teams voice providers can operate in Azure Government or meet federal compliance requirements.

When evaluating providers, make sure they:

• Support DRaaS specifically for GCC High, not just commercial Microsoft 365 or Microsoft GCC
• Use U.S.-based infrastructure and U.S.-screened personnel, in line with GCC High expectations
• Can support environments subject to DFARS, ITAR, and CMMC, as required by your contracts
• Understand Azure Government routing and identity constraints
  
  

Providers that only operate in the commercial cloud, or that treat GCC High as an extension of standard Teams Phone, are unlikely to meet these requirements. At this stage, you should also confirm that the provider’s Session Border Controller (SBC) is certified for Microsoft Teams and compatible with GCC High environments.

Step 3: Connect Microsoft Teams to Your Direct Routing Provider

Establish the technical connection between Microsoft Teams in GCC High and the provider’s voice infrastructure. This process is typically handled jointly by your internal IT team and the DRaaS provider. It generally includes:

• Deploying or connecting to a Microsoft-certified SBC that supports GCC High and Azure Government
• Configuring PSTN gateways in the Teams Admin Center for your GCC High tenant
• Setting up voice routing policies, dial plans, and number normalization rules appropriate for your organization
• Assigning voice policies to users who you’re enabling calling for
  
  

Because GCC High has stricter identity and routing constraints than the commercial cloud, configurations must align specifically with government cloud requirements, not generic Teams Phone documentation. A provider experienced with GCC High DRaaS should guide you through this step and validate that routing, security, and compliance controls are correctly in place.

Step 4: Test, Validate, and Enable Users

Before rolling out calling to users, it’s important to thoroughly test and validate your setup inside GCC High. Your testing should include:

• Inbound and outbound PSTN calling
• Emergency calling, including location-based routing where required
• Voicemail functionality
• Call queues and auto attendants, if used
• PSTN audio conferencing, which is also delivered through Direct Routing in GCC High
  
  

Once testing is complete, start onboarding users for calling in GCC High. Assign phone numbers, apply the appropriate Teams Phone and voice routing policies, and confirm that users are correctly enabled for PSTN calling. Because GCC High environments often support regulated workloads, it’s also important to provide basic guidance on call handling, emergency calling behavior, and any GCC High–specific differences users should be aware of. A brief onboarding step helps ensure that calling works as expected and reduces confusion during initial rollout.

Common Mistakes and Practical Tips

Even when the overall architecture is sound, Teams Direct Routing deployments in GCC High can run into problems if you overlook a few common issues. Below are some of the most common mistakes we see, followed by some guidance on how to avoid them.

Mistake 1: Assuming Commercial Teams Tutorials Apply to GCC High

One of the most common mistakes organizations make is assuming that commercial Microsoft Teams tutorials apply to GCC High. GCC High runs on Azure Government, not the commercial cloud, and many features referenced in standard guides (including Microsoft Calling Plans and Operator Connect) simply don’t exist. Commercial Teams documentation frequently references features that don’t exist in GCC High, which can send teams down setup paths that simply aren’t supported.

Mistake 2: Choosing a Commercial-Only Voice Provider

Another frequent issue is selecting a voice provider that only supports commercial Microsoft 365. Many carriers are unable to meet GCC High requirements around U.S.-only infrastructure, screened personnel, and government cloud routing. Even if a provider supports Teams Phone in the commercial cloud, that does not mean it can operate compliantly in GCC High.

Mistake 3: Mixing GCC High and Non–GCC High Domains or Clouds

Organizations also run into problems when attempting to mix GCC High and non–GCC High domains or identities. Microsoft documentation makes it clear that GCC High tenants cannot rely on commercial cloud identities or external non–GCC High accounts for Teams Phone routing. Mixing cloud environments can break call flows and introduce compliance and security risks.

Practical Tips for a Smoother Deployment

To avoid these pitfalls, work with a provider like Atlantech that has direct experience deploying Teams Direct Routing as a Service in GCC High, rather than adapting commercial voice solutions. Ensure that all call signaling and media remain within U.S.-only infrastructure, and confirm that your voice architecture aligns with the compliance requirements tied to your contracts.

It’s also a good idea to review GCC High–specific compliance guidance, including ITAR and DFARS considerations, before finalizing your deployment. Addressing these requirements upfront can help prevent rework later and ensure your Teams Phone environment holds up under audits and long-term regulatory scrutiny.

Get the Expert Help You Need

DRaaS in GCC High follows a different set of rules than in the commercial Microsoft cloud. Voice services must be designed around Azure Government, U.S.-only infrastructure, and the compliance requirements tied to government and defense contracts.

If you’re not sure whether your current setup is viable, or you want a second set of eyes on your Direct Routing as a Service approach before moving forward, it can help to talk with a team that works in GCC High environments every day.

Atlantech supports Teams DRaaS deployments in GCC High and can help you assess providers, architecture, and compliance considerations before you commit to a build. Request a consultation now.