Telephony Engineer

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)