Lead VOIP Engineer (FreeSWITCH & Kamailio)

Lead VOIP Engineer (FreeSWITCH & Kamailio) Synthflow AI is an enterprise AI agent platform that unifies customer operations across voice, chat, and messaging. Our agents handle routine interactions at scale so teams can focus on high-value work. - Over 20M hours of operations automated - 60% more calls answered vs. non-AI operators - 150M interactions handled, 99.99% uptime Backed by Accel, Atlantic Labs, and Singular. Trusted by 1,000+ customers. Recognized as one of the most promising companies in Germany. LEAD VOIP ENGINEER (FREESWITCH & KAMAILIO) Location: Berlin/Remote Job Type: Full-Time Experience Level: Senior ABOUT THE ROLE We are seeking an experienced VOIP Engineer with a strong background in FreeSWITCH and Kamailio to join our team. The ideal candidate will have extensive experience in SIP-based communications, RTP streaming, and conferencing solutions, along with a deep understanding of high-load production environments. You will be responsible for designing, implementing, and optimizing scalable VOIP solutions while ensuring high availability and performance. RESPONSIBILITIES - Design, deploy, and maintain FreeSWITCH and Kamailio-based VoIP solutions. - Configure and troubleshoot SIP protocols, RTP streams, and media gateways. - Monitor and optimize high-load production FreeSWITCH and VOIP systems. - Implement and manage SIP monitoring tools like Homer or other real-time debugging solutions. - Develop and fine-tune call routing, failover mechanisms, and load balancing strategies. - Ensure security, scalability, and redundancy in the VoIP infrastructure. - Troubleshoot and resolve VoIP-related issues in production environments. - Collaborate with development, DevOps, and support teams to improve system performance. - Work with SIP Trunks, SBCs (Session Border Controllers), and Media Servers. - Implement WebRTC-based voice and video solutions. - Document system configurations, troubleshooting guides, and best practices. REQUIREMENTS - 5+ years of experience in VOIP engineering, particularly with FreeSWITCH and Kamailio. - 3 years of experience with k8s on production systems is a must have. - Strong expertise in SIP protocol, RTP streaming, and VoIP call flows. - Experience working in high-load production FreeSWITCH environments. - Hands-on experience with Homer SIP capture or similar SIP monitoring tools. - Deep understanding of NAT traversal, STUN/TURN, WebRTC, and ICE frameworks. - Strong knowledge of load balancing, failover strategies, and traffic optimization. - Proficiency in Linux administration, networking, and troubleshooting. - Experience with database integration (Redis, PostgreSQL, or NoSQL solutions). - Familiarity with WebRTC, Asterisk, OpenSIPS, or RTP Proxy is a plus. - Ability to write Bash/Python (or Golang) scripts for automation and monitoring. - Strong problem-solving skills and ability to work in highly available and scalable environments. Founded in Berlin in 2023 by serial entrepreneurs Albert Astabatsyan, Hakob Astabatsyan, and Sassun Mirzakhan-Saky, Synthflow AI democratizes access to advanced voice AI with a no-code platform that lets enterprises easily create, deploy and scale natural-sounding, cost-effective voice agents tailored to their business needs.