Requirements: Senior-level experience in backend or full-stack development; Strong knowledge of Python or TypeScript/Node.js; Hands-on production experience with VoIP and SIP telephony; Experience building IVR systems, voice bots, or LLM-powered voice agents; Understanding of STT, TTS, turn-taking, tool calling, and real-time voice processing; Experience integrating LLMs and third-party systems into production; Working knowledge of Asterisk or a similar PBX; Strong problem-solving, ownership, and communication skills. Responsibilities: Develop and improve the voice agent, including conversation flows, patient verification, fallback scenarios, and call transfers; Build backend services and integrations with pharmacy management systems; Maintain the telephony layer, including SIP, RTP, codecs, DTMF, and PBX integrations; Optimize STT, LLM, and TTS pipelines for performance, accuracy, latency, and cost; Implement monitoring, call tracing, quality evaluation, and regression testing; Investigate production issues and contribute to architectural decisions.