Senior Software Developer
<p><b>Salary: £65,000 - 65,000 per year</b></p>
<b>Requirements:</b>
<ul><li>Strong, hands-on experience with SIP/VoIP technologies and protocols (e.g. SIP, SDP, RTP, RFC2833/4733)</li><li>5 years experience developing in Python or another object-oriented language</li><li>Solid understanding of object-oriented design principles</li><li>Experience building and consuming HTTP/REST APIs</li><li>Familiarity with Python frameworks and tooling such as Flask or Django, Pytest, SQLAlchemy, Marshmallow</li><li>Strong background in secure systems design (software and network level)</li><li>Proven experience using Wireshark for SIP/RTP analysis and fault-finding</li><li>Version control experience with Git-based platforms</li><li>Containerisation using Docker</li><li>Strong Linux experience (Ubuntu-based systems)</li><li>Excellent communication skills, comfortable working with both technical and non-technical stakeholders</li><li>Desirable / Nice to Have:</li><li>Experience with FreeSWITCH (configuration and/or source code exposure)</li><li>Working knowledge of C or C++</li><li>Experience with Kamailio</li><li>Authentication and authorisation frameworks (OAuth2, Auth0)</li><li>Databases such as MongoDB and MySQL</li><li>CI/CD pipelines (e.g. GitHub Actions)</li><li>Kubernetes, ArgoCD, or similar deployment tooling</li><li>WebRTC experience</li></ul>
<b>Responsibilities:</b>
<ul><li>Design, develop, and enhance a production SIP/VoIP platform and supporting services</li><li>Build additional value-added services and integrations around the core platform</li><li>Develop integrations with external systems, including AI-driven services such as speech recognition, transcription, and analytics</li><li>Ensure secure design and implementation across software and infrastructure</li><li>Diagnose and resolve complex SIP, RTP, and platform-level issues</li><li>Contribute to secure development processes and compliance with recognised security standards (e.g. ISO27001, PCI-DSS)</li><li>Collaborate closely with other engineers and stakeholders, sharing knowledge and best practice</li></ul>
<b>Technologies:</b>
<ul><li>AI</li><li>ArgoCD</li><li>CI/CD</li><li>Cloud</li><li>Django</li><li>Docker</li><li>Flask</li><li>Git</li><li>GitHub</li><li>HTTP</li><li>Kubernetes</li><li>Linux</li><li>MongoDB</li><li>MySQL</li><li>Network</li><li>Python</li><li>REST</li><li>Security</li><li>Ubuntu</li><li>pytest</li></ul>
<p><b>More:</b></p>
<p>We are a well-established technology business with a strong reputation in communications and cloud-based solutions, offering a hybrid working model that includes one day a month in the office. Our team comprises highly skilled developers focused on the evolution of a large-scale SIP platform and its APIs. We provide a competitive salary of up to £65,000 depending on experience, alongside benefits such as 24 days of annual leave plus bank holidays, a pension plan, private medical insurance, a birthday day off, and opportunities for paid volunteering. If you are an experienced developer seeking to work on technically challenging, real-time systems in a supportive and forward-thinking environment, we would love to hear from you.</p>
<p>last updated 8 week of 2026</p>
<b>Requirements:</b>
<ul><li>Strong, hands-on experience with SIP/VoIP technologies and protocols (e.g. SIP, SDP, RTP, RFC2833/4733)</li><li>5 years experience developing in Python or another object-oriented language</li><li>Solid understanding of object-oriented design principles</li><li>Experience building and consuming HTTP/REST APIs</li><li>Familiarity with Python frameworks and tooling such as Flask or Django, Pytest, SQLAlchemy, Marshmallow</li><li>Strong background in secure systems design (software and network level)</li><li>Proven experience using Wireshark for SIP/RTP analysis and fault-finding</li><li>Version control experience with Git-based platforms</li><li>Containerisation using Docker</li><li>Strong Linux experience (Ubuntu-based systems)</li><li>Excellent communication skills, comfortable working with both technical and non-technical stakeholders</li><li>Desirable / Nice to Have:</li><li>Experience with FreeSWITCH (configuration and/or source code exposure)</li><li>Working knowledge of C or C++</li><li>Experience with Kamailio</li><li>Authentication and authorisation frameworks (OAuth2, Auth0)</li><li>Databases such as MongoDB and MySQL</li><li>CI/CD pipelines (e.g. GitHub Actions)</li><li>Kubernetes, ArgoCD, or similar deployment tooling</li><li>WebRTC experience</li></ul>
<b>Responsibilities:</b>
<ul><li>Design, develop, and enhance a production SIP/VoIP platform and supporting services</li><li>Build additional value-added services and integrations around the core platform</li><li>Develop integrations with external systems, including AI-driven services such as speech recognition, transcription, and analytics</li><li>Ensure secure design and implementation across software and infrastructure</li><li>Diagnose and resolve complex SIP, RTP, and platform-level issues</li><li>Contribute to secure development processes and compliance with recognised security standards (e.g. ISO27001, PCI-DSS)</li><li>Collaborate closely with other engineers and stakeholders, sharing knowledge and best practice</li></ul>
<b>Technologies:</b>
<ul><li>AI</li><li>ArgoCD</li><li>CI/CD</li><li>Cloud</li><li>Django</li><li>Docker</li><li>Flask</li><li>Git</li><li>GitHub</li><li>HTTP</li><li>Kubernetes</li><li>Linux</li><li>MongoDB</li><li>MySQL</li><li>Network</li><li>Python</li><li>REST</li><li>Security</li><li>Ubuntu</li><li>pytest</li></ul>
<p><b>More:</b></p>
<p>We are a well-established technology business with a strong reputation in communications and cloud-based solutions, offering a hybrid working model that includes one day a month in the office. Our team comprises highly skilled developers focused on the evolution of a large-scale SIP platform and its APIs. We provide a competitive salary of up to £65,000 depending on experience, alongside benefits such as 24 days of annual leave plus bank holidays, a pension plan, private medical insurance, a birthday day off, and opportunities for paid volunteering. If you are an experienced developer seeking to work on technically challenging, real-time systems in a supportive and forward-thinking environment, we would love to hear from you.</p>
<p>last updated 8 week of 2026</p>