Unavailable codes

Can you clarify your question? What are those unavailable codes for?

The status of the phone, in example.... Available , On Vacation , In a meeting, On Lunch Break.... etc....

Where in the admin portal do we add these status's ?

Those are user's presence statuses (including the user telephony statuses). You can read and update via APIs or using RingCentral apps (RC app or RingCentral phone app). Right now, you cannot add custom status.

https://developers.ringcentral.com/api-reference/Presence/readUnifiedPresence