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...