Senior / Experienced Software Developer (VoIP / SIP)

Location: Guildford (Hybrid) – must live within a 2-hour commute
Salary: £55,000 – £65,000 (DOE)

The Opportunity

An established technology business is looking for a Senior / Experienced Developer to join a small, specialist software team. You’ll help evolve an enterprise-level SIP platform and build secure, scalable services and integrations.

The Role

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)

Key Skills & Experience

Strong SIP / VoIP protocol knowledge (SIP, SDP, RTP)
5+ years’ experience with Python or another OO language
REST APIs, Flask/Django and secure systems development
Linux (Ubuntu), Docker and Git-based workflows
Wireshark for SIP/RTP troubleshooting
Excellent communication skills

Desirable

FreeSWITCH, Kamailio or WebRTC
C/C++, OAuth2/Auth0
CI/CD, Kubernetes, MongoDB or MySQL

Benefits

24 days’ holiday + bank holidays
Hybrid Working (1 day per month in office)
Pension, Life Insurance & Private Medical
Birthday & volunteering day off
Discounts & Cycle to Work scheme

The client is looking to fill this opportunity immediately, so please apply ASAP or feel free to drop me an email with any questions to owen @ serlimited . com.

SER-IN