You did not provide enough information to give you a definite answer. Microsoft has different licenses, called CALs, such as per device, per user, per server. Everyone or computer that uses any services for the server requires a CAL. Depending on your CALs, each external dial in connection can require a separate CAL. So, you really need to check how your server is licensed, and how your external `connectors? are connecting to you system.
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