Call2Teams - Customers
As an end Customer you cannot amend your own licences via the Call2Teams portal.
You will need to contact your supplier to request these as they are added at the Account Management level.
You can see how many licences you have available and whether any of your users are unlicenced, from the Users tab in your portal. Failing that, you would need to refer to your supplier.
Microsoft Direct Customers
Viewing and modifying the subscription takes place within the Office 365 admin center
Goto (Show all) Billing -> Products and Services -> Apps
The “Add/remove licences” provides for the customer to change the number of users paid. A reduction of licence count will effect a pro-rata refund on unused subscriptions.
A licence increase/decrease should be effective immediately
The customer can view the new licence subscription directly in the Call2Teams portal also