Are you a seasoned developer with a passion for building robust, real-time communications platforms? Looking for a role where you can work on complex, enterprise-grade systems while still being close to the technical detail?

This is an opportunity to join a well-established technology business with a strong reputation in communications and cloud-based solutions. You’ll be part of a small, highly skilled development team working on the evolution of a large-scale SIP platform and its associated APIs, with plenty of scope to influence design, tooling, and future direction.

Working closely with the Development Manager, you’ll play a key role in enhancing and extending an existing SIP and VoIP platform used in production environments. This is a hands-on role suited to an experienced developer who enjoys solving complex protocol-level problems, building secure services, and integrating with third-party systems.

You’ll contribute across the full software lifecycle from design and development through to troubleshooting live issues, while helping to improve development standards, security practices, and platform resilience.

• Design, develop, and enhance a production SIP/VoIP platform and supporting services
• Build additional value-added services and integrations around the core platform
• Develop integrations with external systems, including AI-driven services such as speech recognition, transcription, and analytics
• Ensure secure design and implementation across software and infrastructure
• Diagnose and resolve complex SIP, RTP, and platform-level issues
• Contribute to secure development processes and compliance with recognised security standards (e.g. ISO27001, PCI-DSS)
• Collaborate closely with other engineers and stakeholders, sharing knowledge and best practice

• Strong, hands-on experience with SIP/VoIP technologies and protocols (e.g. SIP, SDP, RTP, RFC2833/4733)
• 5+ years’ experience developing in Python or another object-oriented language
• Solid understanding of object-oriented design principles
• Experience building and consuming HTTP/REST APIs
• Familiarity with Python frameworks and tooling such as Flask or Django, Pytest, SQLAlchemy, Marshmallow
• Strong background in secure systems design (software and network level)
• Proven experience using Wireshark for SIP/RTP analysis and fault-finding
• Version control experience with Git-based platforms
• Containerisation using Docker
• Strong Linux experience (Ubuntu-based systems)
• Excellent communication skills, comfortable working with both technical and non-technical stakeholders

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Desirable

• Experience with FreeSWITCH (configuration and/or source code exposure)
• Working knowledge of C or C++
• Experience with Kamailio
• Authentication and authorisation frameworks (OAuth2, Auth0)
• Databases such as MongoDB and MySQL
• CI/CD pipelines (e.g. GitHub Actions)
• Kubernetes, ArgoCD, or similar deployment tooling
• WebRTC experience

• Salary up to £65,000 depending on experience
• Hybrid working model
• 24 days’ annual leave plus bank holidays
• Pension and life assurance
• Private medical insurance
• Birthday day off and paid volunteering day
• Cycle to Work scheme
• Retail and lifestyle discount programmes

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Interested?‍

• If you’re an experienced developer looking to work on technically challenging, real-time systems in a supportive and forward-thinking environment, we’d love to hear from you. Apply now to learn more.