Engineering, Voice AI

telli

ABOUT US Every 10 minutes, 18 million conversations happen between businesses and consumers around the world. For decades, the consumer side of those conversations sucked: long queues, robotic menus, repeated explanations, and advice that is often unhelpful. Most people today still cannot simply say what their problem is in natural language when communicating with businesses. AI changes that. For the first time, companies can have natural conversations with customers at massive scale. Every B2C company - from energy providers to telcos to insurers - will use AI agents to talk to their customers. The number of conversations businesses will handle is going to explode in the coming years. At telli, we are solving the challenges that come with that shift. Today, leading B2C companies like Sky are already using telli to deploy thousands of voice agents to provide their customers with a new experience. But building a first voice agent is easy, getting it to drive real outcomes for customers and businesses is the hard part. telli helps companies build, deploy, and improve consumer-facing AI voice agents at scale. This will become one of the most important software categories of the next decade, and we intend to win it. We are a small, AI-pilled team that likes to solve hard problems. Be it engineering, product, or GTM - we build, experiment, and move fast, while heavily leveraging the capabilities of AI models. All of us like to challenge ourselves and take real ownership over what we do, all while still staying humble and keeping a low-ego culture. Check out our principles to see how we work. about the role This is role for engineers who care about velocity and solving real customer problems. You won't just ship code; you will own projects end-to-end, make core product and technical decisions, and shape the trajectory of this company. As a member of the engineering team you might: * Manage product features end-to-end, we don’t have PMs you really need to own the entire product lifecycle * Make trade-offs what to not ship, shipping is becoming easy but building the right thing is still hard * Polish and iterate on features such that they are delightful to use for customers * Build reliable and scalable systems and own critical parts of the core infrastructure * Solve novel problems that come from working with Voice AI and scaling to millions of daily calls * Evaluate different models and ensure we push the limits of the technology for our customers what we look for we believe that today, engineers need to not just know how to ship code, but also ensure we work on the right problems. These are the core skills we look for in the interview processes: * Velocity - everything you do, you do with speed * High Agency - "I’ll figure it out" mentality * High Ownership - Nobody has to tell you what to do, you just do things * First Principles Thinking - You don’t take what people say at face value. You make sure you understand the underlying problem * AI-pilled - You are heavily leveraging AI in your work * Strive in ambiguity - You are able to jump into novel ambiguous problem, understand the reason and solve it * Team thinking - You optimize for the eng org output, not personal what may not make you a good fit * you prefer a remote-first environment * you want to be told exactly what to do * you mostly care about the tech, not business outcomes * you want to work 9-5 perks * very competitive pay + equity package * access to any (AI) tools * free dinners if you stay late * urban sports * relocation support if you don’t live in Berlin

Synthflow AI

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. About the role: We’re looking for a Senior Python Engineer to craft reliable, production-ready software and backend systems, with a strong emphasis on databases, scalable APIs, and engineering fundamentals. Your responsibilities will include: * Develop and maintain our backend infrastructure, focusing on scalability, performance, and reliability. * Design and evolve data models and persistence layers with a strong focus on PostgreSQL and database best practices (schema design, migrations, query performance, indexing, transactions). * Build and maintain enterprise-grade APIs (e.g., FastAPI), including versioning, authentication/authorization, and observability. * Engage in pair programming to improve code quality and collaboration. * Manage deployments and environments using Kubernetes and GitOps practices (ArgoCD). * Conduct code reviews, providing constructive feedback and upholding best practices. * Contribute to product delivery end-to-end, including occasional work on front-end features when needed. You have: * 5+ years of experience as a Python developer, shipping production systems. * Strong experience building scalable and extensible data infrastructure. * Deep familiarity with relational databases, especially PostgreSQL (performance tuning, migrations, transactions). * Experience building and maintaining enterprise-grade APIs with FastAPI. * Hands-on experience running production workloads on Kubernetes. * Experience with Argo CD (GitOps deployment workflows). * Experience with GitHub Actions. * Proficiency in cloud environments (preferably GCP or AWS). Nice to have: * Ability to contribute to front-end work (not necessarily a front-end specialist), ideally with React/TypeScript. * Golang experience, with willingness to contribute to our orchestration stack, which is built in Go What we offer: * Autonomy at speed: High-ownership roles in a fast-moving startup. * Engineering-first environment: Work on foundational systems that directly impact reliability and scale. * Career growth: Scale your impact as the company grows. * Rewarding package: Competitive pay, equity options, and comprehensive benefits that reflect your skills and experience. 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.

Synthflow AI

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.