What Microsoft 365 licenses do we need before we can add GCC High Teams calling?

Adding Teams calling to a GCC High tenant requires a Microsoft 365 GCC High enterprise license (E3 or E5) for each user who will make or receive calls. GCC High Business-tier licenses are not available. If the organization uses E5 GCC High, Teams Phone is included. If using E3 GCC High, a separate Teams Phone add-on license is required per user.

For audio conferencing, two additional license types are needed: one Audio Conferencing GCC High tenant-level license for the organization, and individual Audio Conferencing GCC High per-user licenses for each person who needs dial-in or dial-out conferencing capability. These audio conferencing licenses should not be assigned to users until the Direct Routing provider has fully configured the service and set up dial-in numbers, because premature license assignment can cause provisioning issues where the dial pad does not appear in the Teams client. All GCC High licenses are sold through authorized Microsoft resellers via Volume Licensing only. No trials are available, and organizations must pass Microsoft's eligibility validation before purchasing.