Migrating to Microsoft Teams Phone for GCC High: How to Transition Without Downtime

Your legacy PBX system or non-compliant VoIP solution is putting your government contracts at risk. You know you need a new solution, but migrating to a new phone system can be complex and disruptive, especially when compliance and security are at stake.

Government contractors and DoD suppliers must ensure a smooth transition to Microsoft Teams Phone for GCC High while avoiding downtime. A poorly planned migration can cause service interruptions, security gaps, and compliance failures. Microsoft Teams Phone for GCC High provides a secure, seamless voice solution — but only with the right migration strategy.

This guide outlines a step-by-step migration process, helping organizations move to Microsoft Teams Phone for GCC High without service disruptions while highlighting how Atlantech Online ensures a smooth transition.

Why Government Contractors Are Migrating to Microsoft Teams Phone for GCC High

The Problem with Legacy PBX & Traditional VoIP

Many government contractors still rely on legacy PBX systems or traditional VoIP, both of which pose security, compliance, and operational challenges:

• Security vulnerabilities – Traditional VoIP and PBX systems lack encryption and DoD-compliant security controls for handling Controlled Unclassified Information (CUI).
• High maintenance costs – Legacy PBX systems require on-premises hardware, frequent updates, and costly IT resources to maintain.
• Scalability issues – Traditional PBX and VoIP solutions struggle to support multi-site operations and remote teams, limiting flexibility.
  
  

Why Microsoft Teams Phone for GCC High Is the Future

Government contractors and DoD suppliers must meet strict security and compliance requirements when handling Controlled Unclassified Information (CUI) and other sensitive data. 

Microsoft Teams Phone for GCC High is designed specifically to address these needs, ensuring full compliance with ITAR, DFARS, and CMMC 2.0 mandates. By adopting this solution, organizations can securely manage voice communications while staying in line with evolving federal regulations.

Here are a few key advantages of this solution:

• Seamless integration with Microsoft 365 GCC High applications, including Outlook, SharePoint, OneDrive, and Teams. This level of integration allows government agencies and contractors to streamline communication, collaboration, and data sharing while maintaining strict security and access controls. 
• Unlike traditional phone systems that operate in silos, Microsoft Teams Phone consolidates voice, video, and messaging into a unified, compliant communication environment.
• Migrating to Microsoft Teams Phone for GCC High eliminates the need for on-premises PBX systems, significantly reducing IT overhead and long-term maintenance costs. 
• Its ability to support secure PSTN calling via Direct Routing. Because Microsoft does not offer Calling Plans for GCC High, organizations must use Direct Routing through an approved government VoIP provider to enable secure, compliant voice communication. 

Most importantly, as compliance requirements tighten and traditional VoIP solutions fail to meet DoD security mandates, Microsoft Teams Phone and Audio Conferencing for GCC High has emerged as the future of secure government communication. 

Why Now Is the Best Time to Migrate

For government contractors and DoD suppliers, delaying the transition to Microsoft Teams Phone for GCC High is no longer an option. With CMMC 2.0 enforcement ramping up, organizations must ensure their communication systems meet the required security standards or risk losing their ability to bid on or retain DoD contracts. 

Additionally, the rapid expansion of remote and hybrid workforces has fundamentally changed how government contractors operate. More employees are working from multiple locations, including home offices and secure facilities, requiring a flexible, cloud-based communication system that meets federal security standards.

Transitioning to Teams Phone and Audio Conferencing for GCC High now allows contractors and suppliers to move proactively to a fully compliant, future-proofed communication system rather than waiting until regulatory pressures and security risks become more urgent.

Key Challenges in Migrating to Microsoft Teams Phone for GCC High

Compliance & Security Risks

Government contractors must ensure 100% adherence to CMMC, ITAR, and DFARS mandates when migrating to a new phone system. Many VoIP providers lack the necessary compliance certifications, putting organizations at risk of contract loss and regulatory violations.

Call Routing & Number Porting Complexity

Transferring existing phone numbers without downtime is a major concern. Government contractors must follow strict Direct Routing configuration procedures to avoid disruptions. Working with a certified migration partner is essential to ensure a smooth transition.

User Adoption & Training

Employees must be trained to use Microsoft Teams Phone effectively to avoid productivity loss. IT teams also need to configure security settings, access controls, and compliance monitoring to maintain adherence to federal regulations.

Downtime & Service Disruptions

A poorly planned migration can result in missed calls, lost data, and service outages. Organizations need a structured, step-by-step migration strategy to minimize risk and ensure continuity.

Step-by-Step Guide to Migrating to Microsoft Teams Phone for GCC High

“There are a few that really boil down to planning for the time it takes for everything to happen, and working with the right partner who knows this and can prepare you for it to set the right expectations: 

1. Allocating time necessary to obtain approval from Microsoft for a GCC High approval and license acquisition.  
2. Once you have your GCC High domain and licensing, allocate the time to work closely with your phone vendor to complete all the steps necessary to turn up phone service.  
3. Thoroughly testing the phone service and audio conferencing prior to end-user roll-out.
4. Failing to set up 911 location services in the MS Teams Admin portal.

Again, these issues can be mitigated by working with a partner like Atlantech Online who has done the due diligence to understand the steps in deployment, what’s required for each step, and how long they can take.” -Ed Fineran, President, Atlantech Online

1. Assess Your Current Communication Infrastructure

Before migrating, evaluate your existing phone systems, VoIP solutions, and compliance gaps. Identify which systems need to be replaced, upgraded, or integrated into your new Microsoft Teams Phone deployment.

2. Procure Microsoft 365 GCC High Licensing

Microsoft Teams Phone for GCC High requires specific licensing options:

• Microsoft 365 E5 GCC High (Includes Teams Phone)
• Microsoft 365 E3 GCC High (Requires Teams Phone add-on)
• Standalone Teams Phone License

Working with a Microsoft-approved provider (like Atlantech Online) ensures proper license configuration and a smooth deployment.

3. Choose a Direct Routing Provider

Because GCC High does not support Microsoft Calling Plans or Operator Connect, organizations must enable Direct Routing through an approved VoIP provider. Atlantech Online specializes in GCC High Direct Routing, ensuring secure, compliant PSTN connectivity.

4. Set Up Call Routing & Security Policies

• Configure Session Border Controller (SBC) settings for encryption and compliance. A key benefit of Atlantech Online’s service is that we provide the SBC. You just provide us the Microsoft 365 GCC licensing.
• Establish call forwarding, voicemail, and access control policies to maintain security.
  
  

5. Port Existing Phone Numbers to Microsoft Teams

• Work with Atlantech Online’s expert number porting team to transfer numbers without downtime.
• Test phone number transitions before fully decommissioning your old system.
  
  

6. Conduct Compliance Testing & Security Audits

• Verify encryption, call routing security, and CMMC compliance settings.
• Test network resilience and failover configurations to ensure high availability.
  
  

7. Train Employees & Launch Teams Phone

• Provide end-user training on Microsoft Teams Phone features and functionality.
• Offer IT administrator training on security settings, compliance monitoring, and call management.
  
  

A Secure, Seamless Transition to Microsoft Teams Phone for GCC High

Why a Proper Migration Plan Matters

Migrating to Microsoft Teams Phone for GCC High requires careful planning to prevent downtime. Government contractors must follow strict security and compliance protocols to protect their contracts and sensitive data. A well-executed migration ensures a seamless transition to a fully compliant, secure communication system.

Atlantech Online’s Migration Services for Government Contractors

1. We gather all the pertinent information from you.
2. Then, we build the customer tenant in your portal.
3. Then, we guide you through the AzureBot Setup.
4. Next, we deliver customer portal access and Active Directory synchronization services.
5. Finally, we enable call routing and emergency services.
   
   

Take Action Now: Start Your Migration with Atlantech Online

Migrating to Microsoft Teams Phone for GCC High is essential for ensuring compliance with ITAR, DFARS, and CMMC 2.0 mandates while maintaining secure, encrypted communication. 

A seamless transition from legacy PBX or non-compliant VoIP requires expert planning, compliance oversight, and a trusted Direct Routing provider.

Atlantech Online specializes in secure, government-compliant deployments, helping contractors migrate without downtime or security risks. 

Get the expertise, support, and step-by-step guidance needed for a smooth transition so your organization stays compliant and connected. Schedule a Free Consultation with Atlantech Online today to start your migration with confidence.