Microsoft Teams calling in GCC High works through Direct Routing. A Microsoft-certified session border controller (SBC) connects your GCC High tenant to a phone carrier over encrypted SIP, so users place and receive outside calls in Teams. Intuity UC provides that SBC and carrier connection from its own Azure GCC High instance.
Why GCC High uses Direct Routing
Microsoft delivers Teams Phone System and Audio Conferencing in GCC High and DoD through Direct Routing. Microsoft’s GCC High service description names Direct Routing as the delivery method, and Microsoft Calling Plans are not part of it.
So every GCC High calling deployment needs a carrier and an SBC that can connect to Microsoft’s government environment. (New to the platform? Start with what GCC High is.)
What the call path looks like
A GCC High call has four parts:
| Component | What it does | Who provides it |
|---|---|---|
| Teams Phone license | Turns on calling features for each user | Microsoft, through your GCC High licensing |
| GCC High tenant | Hosts Teams; meeting media is processed in the USGov Arizona and USGov Texas regions | Microsoft |
| Certified SBC | Connects Teams to the carrier over SIP/TLS on port 5061, to sip.pstnhub.gov.teams.microsoft.us | Intuity UC (hosted in Intuity UC’s Azure GCC High instance) |
| Carrier (PSTN) | Phone numbers, dial tone, 911 and audio-conference dial-in | Intuity UC |
Because GCC High runs only in U.S. data centers, Microsoft publishes a single SIP connection point for it, with no secondary or tertiary endpoints. Microsoft supports Direct Routing only with certified SBCs.
Setup steps
- Confirm the tenant and licenses. Make sure you are in a GCC High tenant (not GCC or commercial) and that users have Teams Phone licenses.
- Choose a GCC High Direct Routing provider. Confirm its SBC is Microsoft-certified and runs inside a GCC High or Azure Government boundary. Use these eight questions to compare providers.
- Pair the SBC with your tenant. This needs a verified domain, an SBC FQDN and a trusted TLS certificate.
- Build routing. Create voice routing policies, PSTN usages and dial plans.
- Port your numbers and set up emergency calling with each user’s dispatchable location.
- Turn on Audio Conferencing last. Microsoft recommends completing Direct Routing before assigning Audio Conferencing licenses in GCC High.
- Pilot, then cut over by site or department.
Where projects stall
The slow parts are rarely Teams itself. They are number porting across several carriers, analog devices (fax, elevators, alarms) that need their own plan, and call flows such as hunt groups and auto attendants that need redesign. Plan for those in discovery, not at cutover.
How Intuity UC delivers GCC High calling
Intuity UC provides managed Direct Routing for GCC High tenants. The SBC is hosted in Intuity UC’s Azure GCC High instance, so there’s no SBC to buy, install or patch on site. Calls are encrypted with TLS and SRTP across the Intuity network, operations and 24/7 support are U.S.-based, and pricing is a fixed monthly rate rather than per minute. See Intuity UC’s GCC High PSTN service.
Frequently asked questions
Does Microsoft offer Calling Plans in GCC High?
No. Microsoft delivers Teams Phone System and Audio Conferencing in GCC High through Direct Routing, using a certified SBC and a third-party carrier such as Intuity UC.
Do I need to buy my own SBC for GCC High?
No. With a managed provider such as Intuity UC, the certified SBC is hosted for you. Intuity UC runs it in its own Azure GCC High instance.
Can I keep my existing phone numbers?
Yes. Numbers are ported from your current carrier to the GCC High calling provider and then assigned to Teams users.
Does Teams audio-conference dial-in work in GCC High?
Yes. Audio Conferencing in GCC High is delivered through Direct Routing. Microsoft recommends finishing Direct Routing setup before assigning Audio Conferencing licenses.
Where is GCC High Teams meeting media processed?
Microsoft states that media processors for Teams meetings in GCC High are located only in the USGov Arizona and USGov Texas regions.
Sources:
Microsoft: Plan Direct Routing ·
Microsoft: Plan for media bypass with Direct Routing ·
Microsoft: GCC High and DoD service description ·
Microsoft: GCC High endpoints