Synthflow AI is a no-code platform for deploying voice AI agents that automate phone calls across contact center operations and business process outsourcing (BPO) at scale. We help mid-market and enterprise companies manage routine calls to save teams time and resources.
Our agents have already delivered measurable impact:
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Over 5 million hours of contact center operations saved
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35% more calls answered compared to non-AI operators
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45 million calls handled with a 99.9% uptime
Backed by Accel, Atlantic Labs, and Singular and trusted by over 1,000 customers, our growth leads an industry shift toward sophisticated and accessible conversational AI.
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
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Design, deploy, and maintain FreeSWITCH and Kamailio-based VoIP solutions.
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Configure and troubleshoot SIP protocols, RTP streams, and media gateways.
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Monitor and optimize high-load production FreeSWITCH and VOIP systems.
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Implement and manage SIP monitoring tools like Homer or other real-time debugging solutions.
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Develop and fine-tune call routing, failover mechanisms, and load balancing strategies.
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Ensure security, scalability, and redundancy in the VoIP infrastructure.
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Troubleshoot and resolve VoIP-related issues in production environments.
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Collaborate with development, DevOps, and support teams to improve system performance.
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Work with SIP Trunks, SBCs (Session Border Controllers), and Media Servers.
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Implement WebRTC-based voice and video solutions.
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Document system configurations, troubleshooting guides, and best practices.
Requirements
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5+ years of experience in VOIP engineering, particularly with FreeSWITCH and Kamailio.
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Strong expertise in SIP protocol, RTP streaming, and VoIP call flows.
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Experience working in high-load production FreeSWITCH environments.
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Hands-on experience with Homer SIP capture or similar SIP monitoring tools.
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Deep understanding of NAT traversal, STUN/TURN, WebRTC, and ICE frameworks.
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Strong knowledge of load balancing, failover strategies, and traffic optimization.
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Proficiency in Linux administration, networking, and troubleshooting.
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Experience with database integration (Redis, PostgreSQL, or NoSQL solutions).
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Familiarity with WebRTC, Asterisk, OpenSIPS, or RTP Proxy is a plus.
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Ability to write Bash/Python (or Golang) scripts for automation and monitoring.
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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.
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