Software Engineer
Posted 1 week ago by SmartSourcing plc
£450 Per day
Inside
Hybrid
Nationwide
Summary: The role of C# Software Engineer involves developing complex real-time systems within an Agile team, focusing on SIP signaling and session management, real-time media handling, and secure communications. The position requires working remotely with one day a month on-site in Rugby and is classified as inside IR35. Candidates must have experience with 3GPP-compliant User Equipment and be eligible for BPSS clearance.
Key Responsibilities:
- Develop C# components for high-concurrency SIP sessions.
- Implement RTP/RTCP media handling for Mission Critical Voice and Video.
- Build handlers for MCData services using HTTP and SIP MESSAGE requests.
- Integrate OIDC authentication flows and MIKEY-SAKKE encryption for secure media transport.
Key Skills:
- 3+ years of professional experience in C# / .NET Framework / .NET Core.
- Experience with WCF, SignalR, EF, ASP.NET, WebAPI.
- Solid understanding of the SIP Protocol Stack and experience with RTP/RTCP.
- Proficiency in parsing complex XML schemas and handling multipart/mixed MIME bodies.
- Strong grasp of OOP, SOLID principles, and modern CI/CD workflows.
Salary (Rate): £450/day
City: Rugby
Country: United Kingdom
Working Arrangements: hybrid
IR35 Status: inside IR35
Seniority Level: Mid-Level
Industry: IT
C# Software Engineer, Remote, 12 month contract, Inside IR35
Must be eligible for BPSS clearance. Working one day a month on site in Rugby
Real-time system experience is essential for this role, working within an Agile delivery team, you will move beyond standard CRUD applications to solve complex network and real-time communication challenges. You will lead the development of expansion products that interface with 3GPP-compliant User Equipment (UE).
What You’ll Do:
- SIP Signaling & Session Management: Develop C# components for high-concurrency SIP sessions, managing complex headers and MIME bodies to support features like "First-to-Answer" and Group Regroups.
- Real-Time Media Plane: Implement RTP/RTCP media handling for Mission Critical Voice (MCPTT) and Video (MCVideo), ensuring seamless floor control (transmission rights) in half-duplex environments.
- Data & Configuration: Build handlers for MCData services (SDS, File Distribution) using HTTP and SIP MESSAGE requests, and manage XCAP retrieval logic for XML configuration documents.
- Secure Communications: Integrate OIDC authentication flows and MIKEY-SAKKE encryption to ensure media transport remains secure and resilient.
Essentials skills:
- C# / .NET Framework / .NET Core Mastery: 3+ years of professional experience with a deep focus on asynchronous network programming.
- .NET Frameworks Experience: WCF, SignalR, EF, ASP.NET, WebAPI
- Protocol Expertise: A solid understanding of the SIP Protocol Stack (INVITE, PUBLISH, SUBSCRIBE, etc.) and experience with RTP/RTCP stacks.
- Data Handling: Proficiency in parsing complex XML schemas (XSD) and handling multipart/mixed MIME bodies.
- Software Engineering Principles: Strong grasp of OOP, SOLID principles, and modern CI/CD workflows (Git, Pull Requests, Agile).
Preferred skills:
- 3GPP Standards: Familiarity with TS 24.379 (MCPTT) or related MCX standards.
- Security: Experience with SRTP, TLS, or Key Management lifecycles (KMS).
- Domain Knowledge: Previous experience with UK Police Control Room environments or the Emergency Services Network (ESN).
SmartSourcing are a Disability Confident Employer and we promote, celebrate and value diversity, we are committed to promoting equality and inclusion for all