Requirements 5 to 10 years of experience in VoIP and telephony engineering Deep understanding of SIP protocol including messaging, methods, response codes and SDP, as well as troubleshooting of signaling and media issues including NAT and RTP Knowledge of FreeSWITCH including architecture, dialplan development using Lua or XML, configuration of SIP profiles, gateways and modules such as ESL and Sofia, and performance optimization Experience building utilities, tools, management services for VoIP infrastructure Experience with Go language. Solid understanding of networking including TCP IP, RTP RTCP and traffic analysis using tools such as tcpdump, Wireshark and sngrep Strong Linux administration (Debian or Ubuntu) Nice to have Experience with Kamailio/Opensips or rtpengine Familiarity with CI CD, Docker, Ansible and Kubernetes Experience with large scale telephony systems Experience with Node.js for integration services, event socket (ESL) interaction with FreeSWITCH and REST API development Background in voice biometrics projects

Responsibilities

Design and modernization of the telephony infrastructure Integration with telecom providers in the US, LATAM and Europe Optimization of resources and telecom costs Building call handling systems from scratch for both outbound and inbound traffic Development of integration solutions with the AI platform Driving reliability, scaling and fault tolerance Working with high call volumes using Kamailio/OpenSIPS and rtpengine Participate in 2d and 3d level support duties as well as on-call rotation What we offer The team has built award-winning AI products for tech corporations — devices, voice assistants, products that are actually in the world Cutting-edge tech stack: Speech Technologies, NLP, Generative AI (LLMs, diffusion models), voice-first agentic architecture with privacy-first and on-premises deployment High engineering bar and real ownership — the team cares about what actually works in production, not what looks good in a demo, and you'll see the impact of your work directly Fast career progression — a senior-heavy team and a high volume of real problems means you grow faster than you would anywhere else Startup pace with enterprise stability — real clients, real revenue, no bureaucracy Fully remote across Europe 21 vacation days + public holidays + 5 sick days Private English lessons via Preply Participation in Employee Stock Ownership Plan (ESOP)