A Cisco VOIP developer designs, implements, and troubleshoots Voice Over Internet Protocol (VOIP) systems for businesses using Cisco technologies. Their responsibilities include creating and updating VOIP networks, ensuring interoperability between IP-based systems and traditional telephone systems, and enhancing system performance. They also work on call routing and dial plan management. They ensure system security, provide technical support, and troubleshoot any issues. They need knowledge of Cisco Unified Communications Manager, VOIP protocols like SIP, , MGCP, and networking fundamentals. They may also integrate VOIP systems with other business applications. They work closely with network engineers and other IT professionals.