Cisco Unity Connection, SIP H.323 RTP SRTP protocols, Cisco CUBE, Audiocodes or Oracle SBC, Cisco UCCX Contact Center basics, Route Patterns CSS Partitions Translation Patterns, Cisco IM Presence, Microsoft Teams Calling Direct Routing, Wireshark packet analysis, Webex Calling, Cisco Jabber Webex App, SIP Trunks and Voice Gateways, RTMT CDR Analysis DNA, Basic understanding of SBCs and PSTN integrations, Cisco Expressway, Troubleshooting voice quality and call routing issues