Salary: £30,000 - 55,000 per year Requirements: Strong SIP / VoIP protocol knowledge (SIP, SDP, RTP) 5 years’ experience with Python or another OO language Experience with REST APIs, Flask/Django and secure systems development Proficiency in Linux (Ubuntu), Docker, and Git-based workflows Familiarity with Wireshark for SIP/RTP troubleshooting Excellent communication skills Desirable: Experience with FreeSWITCH, Kamailio or WebRTC Desirable: Knowledge of C/C++, OAuth2/Auth0 Desirable: Familiarity with CI/CD, Kubernetes, MongoDB or MySQL Responsibilities: Design, develop and enhance a SIP/VoIP platform and associated services Build REST APIs and value-add services Integrate with external systems including AI-driven voice, transcription and analytics services Troubleshoot SIP/RTP issues and improve platform reliability Contribute to secure development practices and compliance (ISO27001, PCI-DSS) Technologies: AI CI/CD Django Docker Flask Git Kubernetes Linux MongoDB Python REST Ubuntu MySQL More: We are an established technology business based in Guildford, offering a hybrid working model. We provide a competitive salary of £55,000 – £65,000, depending on experience. Our benefits include 24 days’ holiday plus bank holidays, a pension scheme, life insurance, private medical coverage, as well as additional perks like a birthday and volunteering day off, discounts, and a Cycle to Work scheme. Join our small, specialist software team and help us evolve an enterprise-level SIP platform. last updated 5 week of 2026