Can you share which specific documentation showed that it was XEP-0600? Link please.
Searching on the latest version, I see that it shows XEP-0060: https://developer.cisco.com/docs/finesse/#real-time-events
Real-time events (such as call events, state events, and so on) are sent by the Cisco Finesse Notification Service, using the XEP-0060 Publish-Subscribe extension of the XMPP (Extensible Messaging and Presence Protocol) protocol.
I would like to know where you saw it say XEP-0600 so that we can fix the typo.
I did a google for "XEP-0600" and found this link (not sure if this is only one):
"Finesse clients can interface directly with the Cisco Finesse Notification Service to send subscribe and unsubscribe requests. Clients subscribe to notification feeds published to their respective nodes (such as /finesse/api/User/1000) by following the XEP-0600 standard."