GCC High Processes

Why is Direct Routing the only way to add PSTN calling to a GCC High tenant?

Direct Routing is the only PSTN option in GCC High because Microsoft Calling Plans and Operator Connect do not meet the data sovereignty, personnel screening, and compliance certification requirements of the GCC High environment. Microsoft has not made those services available for GCC High, and there is no announced timeline for that to change.

Microsoft Calling Plans use commercial carrier infrastructure where call routing, metadata storage, and support operations may involve non-U.S. data centers or unscreened personnel. Operator Connect relies on carrier partnerships that have not achieved the necessary certifications for handling ITAR-controlled, DFARS-regulated, or CMMC-scoped voice traffic within the GCC High boundary. Direct Routing solves this by placing the compliance burden on specialized third-party voice providers who operate certified SBCs within Azure Government infrastructure, keep all call data in U.S.-only pathways, and staff their operations with screened U.S. personnel. This architecture gives organizations and their compliance auditors a clear chain of custody for voice communications. Only a small number of carriers are authorized to deliver Direct Routing services for GCC High, because the certification and infrastructure requirements create a high barrier to entry.

Can we add Teams calling to an existing GCC High environment?

Teams calling can be added to an existing GCC High tenant without migrating to a new environment. The process layers Direct Routing voice services on top of the current Microsoft 365 GCC High deployment, keeping all existing configurations, users, and data intact.

Adding Teams calling requires three things: Teams Phone licenses for each user who will make or receive calls (included with E5 GCC High or available as an add-on for E3 GCC High), a compliant Direct Routing provider to manage SBC infrastructure and PSTN connectivity, and configuration of call routing, dial plans, and emergency calling within the Teams Admin Center. The provider handles the SBC deployment and PSTN trunk connection on their end, while the organization's IT administrator assigns phone numbers and calling policies through the existing GCC High management portal. No on-premises hardware is required when using a managed DRaaS provider. The integration connects seamlessly with existing Microsoft 365 GCC High applications including SharePoint, Exchange, OneDrive, and Outlook.

How long does it take to go live with GCC High Teams calling?

Deployment timelines for GCC High Teams calling range from as few as two weeks with a managed DRaaS provider to 12 to 24 weeks for organizations attempting manual SBC deployment and configuration without an experienced provider.

The difference comes down to automation and provider maturity. Managed providers that have pre-built GCC High-certified SBC infrastructure and automated provisioning workflows can onboard organizations quickly because the heavy infrastructure work is already done. The provider configures the tenant connection, sets up call routing, ports existing phone numbers, and deploys the service without the customer needing to stand up any hardware. Manual approaches require procuring, installing, and certifying SBC hardware, configuring Direct Routing from scratch using GCC High-specific FQDNs and certificates, and troubleshooting configuration issues that standard commercial documentation does not address. The customer's readiness also affects timeline: organizations with clean user directories, confirmed licensing, and a clear phone number inventory move faster than those still sorting out their tenant configuration. Atlantech Online positions go-live in weeks rather than months through a managed deployment model that includes white-glove setup, number porting, and SBC configuration.

What happens to our existing phone numbers during a migration to GCC High Teams calling?

Existing phone numbers are ported to the new GCC High Teams calling environment during migration. The porting process transfers ownership of the numbers from the current carrier to the GCC High Direct Routing provider, so the organization keeps its existing numbers without interruption to service.

The voice provider manages the entire porting process, which includes submitting port requests to the current carrier, coordinating the transfer timeline, and configuring the numbers within the GCC High environment. Once porting is complete, the IT administrator assigns numbers to users and sets calling policies through the Microsoft Teams Admin Center. New numbers can also be selected through the GCC High management portal if the organization wants to add lines beyond what it currently has. A managed provider typically handles the porting alongside SBC configuration and infrastructure setup so that users experience minimal downtime during the cutover. Organizations should inventory all existing numbers, identify which ones need to move to GCC High versus which can stay on a commercial system (if using an enclave approach), and work with their provider to establish a porting schedule that avoids disruption to daily operations.