A Webex Calling Professional license includes voicemail entitlement. Auto Attendants, and all other overlay features (eg park, pickup, hunt group, etc.) are not licensed in the current offer structure. The only other user calling cost should be your PSTN service and optionally Webex Go. Workspaces (aka common area phones) are also included at 50% of your user count if you opt for an enterprise agreement; they do have a cost under the named user model.
Additional details are in the ordering guide (partner access required).
