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.