All the agent extensions in the skills are set to be monitored in the Interacation Data server - Voice and Presence as well as the hunt group extension of the skills.
To further verfiy the wallboard stats. If I show the Agent status individually on the wallboard, their status match their current phone state. If I have 3 agents with stats "Ready", I always only get 1 agent shown as available.
I think that wallboard is one of the key feature of CCE