Cucm, Dns, Vlans, DHCP, Cuc, Qos, Tls, Cisco Expressway, IM Presence, NTP, CSR generation, PKI Certificate management, Cisco IOS CLI, Cisco Webex, Call Routing, dial plans, SIP, Cisco CUBE, VMware-based UC deployments, Cisco RTMT, Microsoft Teams Voice, voice gateway concepts, certificate renewal