JavaScript Software Engineer

Salford

Permanent | Full-time

Up to £60,000 per annum (negotiable)

DCS Technology are searching for a JavaScript Software Engineer to join our client and lead the delivery of a JavaScript-driven robust telephony infrastructure. This role offers the opportunity to work deeply with real-time communications technology, influencing architecture, performance, and user experience in a production environment.

Key responsibilities

Design and build a JavaScript-based dial pad UI, using modern frameworks such as React, Vue, or vanilla JavaScript. Integrate the frontend dial pad with a backend PJSIP / pjproject SIP stack via services or bindings. Develop and maintain real-time, event-driven systems supporting voice calling and signalling. Work with WebRTC and ensure effective interoperability with SIP-based systems. Handle real-time audio concerns including microphone input, speaker output, echo cancellation, and latency optimisation. Collaborate on the design and implementation of SIP call flows, media handling, and call state management. Debug SIP signalling and media streams using tools such as Wireshark and SIP trace utilities. Ensure systems are secure, implementing best practices around TLS, SRTP, and authentication. Deploy and support services in Linux-based environments, ensuring stability and performance. Produce and maintain clear technical documentation aligned with development standards and change processes.

Key skills and experience:

Strong JavaScript experience (Node.js and/or browser-based applications). Hands-on experience integrating PJSIP / pjproject via backend services or bindings. Solid understanding of VoIP fundamentals, including SIP, SDP, RTP/RTCP, codecs, and DTMF. Experience working with WebRTC and SIP interoperability. Proven ability to design and implement responsive, user-friendly dial pad interfaces. Experience building event-driven, real-time systems using WebSockets and asynchronous workflows. Familiarity with SIP servers such as Asterisk or FreeSWITCH. Strong debugging skills across signalling and media layers. Comfortable working in Linux environments. Good understanding of security principles relevant to VoIP and real-time communications.

What you get in return:

Salary: Up to £60,000

Benefits: Paid annual leave, pension, wellbeing perks and more

Career Development: Opportunities to grow with a company undergoing rapid expansion across multiple sectors

Interested?

Please submit your CV to Meg Kewley at DCS Engineering via the link provided.

Alternatively, email me at or call (phone number removed).

DCS Recruitment and all associated companies are committed to creating a working environment where diversity is celebrated and everyone is treated fairly, regardless of gender, gender identity, disability, ethnic origin, religion or belief, sexual orientation, marital or transgender status, age, or nationality