1) Logged in agents per DIALER (registration of phone) is already readily available. So I'll assume you mean ...
2) Logged in agents per AGENT WEB (web browser) is not available anywhere. There are ... hints in some of the tables and it could be possible to compile an active list. But there's no single place to "get" a list at present.
That being said: We have an active request from a client to create one. We're investigating the best method. Mostly we're looking at whether we can gather the needed information without altering code.
PS: Why is your BUILD not listed, Dennis? For Shame.