Communication Credits for GCC customers have to be purchased directly on office.com (They are not yet available as a CSP product). Communications Credits are a convenient way to pay for Audio Conferencing and Calling Plan minutes. It helps ensure you and your users are never caught without being able to complete a call.
Communication Credits help ensure you and your users are never caught without being able to:
Dialing out from an Audio Conference meeting to add someone else from anywhere in the world.
Dialing out from an Audio Conference meeting to your mobile phone with the Skype for Business or Microsoft Teams app installed to destinations that aren't already included in your subscription.
Dial any international phone number when you have Domestic Calling Plan subscriptions.
Dial international phone numbers beyond what is included in a Domestic and International Calling Plan subscription.
Dial out and pay per minute once you have exhausted your monthly minute allotment.
To order sign-in to your Office 365 tenant and go to this link Communication Credits for GCC customers