Collaboration Applications
Voice messaging
Unity Connection provides voicemail, auto-attendant, and routing rules. Know the objects: users and templates, call handlers (greetings and menus), search spaces and partitions (search scope), interview handlers for name capture, and distribution lists. Message waiting indication reaches the phone as MWI on/off; if lamps fail, suspect the MWI port, the notification device, or the SIP/SCCP MWI configuration - not the greeting. Port count and licensing are capacity questions, and message-store design matters in multi-cluster deployments.
Presence and messaging
IM&P provides presence, chat, and federation. Presence status is computed from client capabilities, device state (a phone in use), and calendar integration. Traps: assuming presence works without the presence engine and a healthy SIP connection to CUCM, and forgetting that federation requires DNS and certificates on both sides.
Conferencing and contact center
Cisco Meeting Server handles on-premises conferencing with spaces, call bridges, and SIP trunks to CUCM; a Conductor or load balancer fronts scalability. UCCX adds contact center: triggers, scripts, CSQs, resource groups, and skills. Do not confuse UCCX scripting objects with CUCM routing objects.
Supporting applications
Prime Collaboration Deployment for migrations and upgrades, Emergency Responder for E911 location tracking, attendant consoles, and LDAP directory integration (sync plus authentication) round out the domain.
Rule of thumb
For any application question, ask three things: which server holds the data, which protocol carries the feature (SIP, SCCP, XMPP, LDAP, IMAP), and what happens during a publisher outage. That triad eliminates most distractors.