Lead VOIP Engineer (FreeSWITCH & Kamailio)

Stack

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
• ▹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
• ▹Collaborate with development, DevOps, and support teams to improve performance
• ▹Work with SIP trunks, SBCs, and media servers
• ▹Implement WebRTC-based voice and video solutions
• ▹Document system configurations, troubleshooting guides, and best practices

Requirements

• ▹5+ years of VoIP engineering experience, particularly with FreeSWITCH and Kamailio
• ▹3 years of Kubernetes experience on production systems (must have)
• ▹Strong expertise in SIP protocol, RTP streaming, and VoIP call flows
• ▹Experience 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 and networking
• ▹Experience with database integration (Redis, PostgreSQL, or NoSQL)

Nice to have

• ▹Familiarity with WebRTC, Asterisk, OpenSIPS, or RTP Proxy
• ▹Ability to write Bash/Python (or Golang) scripts for automation and monitoring

Soft skills

About the company

Synthflow AI is an enterprise AI agent platform unifying customer operations across voice, chat, and messaging, with 20M+ hours of automated operations, 150M+ interactions handled, and 99.99% uptime. Backed by Accel, Atlantic Labs, and Singular. Founded in Berlin in 2023.