Which providers offer audio conferencing through Direct Routing in a GCC High Microsoft 365 tenant?

Audio conferencing in GCC High is only available through Direct Routing because Microsoft does not provide its standard cloud-based audio conferencing service (dial-in numbers) in the GCC High environment. The voice provider supplies the dial-in phone numbers and conferencing infrastructure as part of the Direct Routing setup.

Providers offering audio conferencing through Direct Routing in GCC High include Atlantech Online, CallTower, HelloTeams, Momentum, and AT&T. CallTower has publicly positioned itself as an early mover in GCC High audio conferencing via Direct Routing. Audio conferencing requires specific licensing: one Audio Conferencing GCC High tenant license for the organization and per-user Audio Conferencing GCC High licenses for each participant who needs dial-in or dial-out capability. These licenses are free but must be explicitly enabled, and they should only be assigned after the Direct Routing provider has completed the conferencing configuration with dial-in numbers. Assigning the licenses before configuration is complete can cause provisioning issues where the dial pad disappears from the Teams client. Organizations evaluating providers should ask specifically about audio conferencing support, because not every GCC High voice provider includes it as a standard capability.