Java Developer

Java Voice Services Developer

Ipswich based- Candidates must be based in the UK, and a commutable distance from our client's office in Ipswich, Suffolk.

Contract until March 2027

Paying upto £360.00 per day (inside IR35)

Our client, a leading global technology organisation, is looking for an experienced Java Voice Services Developer to join a high-profile programme delivering next-generation communications and conversational AI solutions. This is an exciting opportunity for a developer with strong telephony and cloud experience to work at the intersection of voice technologies, AI, and cloud platforms.

The Role

As a Java Voice Services Developer, you will be responsible for designing, developing, and supporting advanced SIP-based voice services while integrating cutting-edge speech and AI technologies. You will collaborate with architects, DevOps teams, and cloud specialists to deliver scalable, high-performance communication platforms.

Key Responsibilities

• Develop, test, and maintain SIP-based voice services using Java, JAIN SLEE, and SIP Servlet frameworks.


• Configure, administer, and optimise FreeSWITCH and/or Asterisk communication platforms.


• Integrate Speech-to-Text, Text-to-Speech, and NLP solutions into live voice applications.


• Deploy and support applications across AWS, Azure, and Google Cloud environments.


• Troubleshoot network, voice quality, latency, and call routing issues using industry-standard tools.


• Support the delivery of innovative conversational AI and voice automation solutions.

Required Skills & Experience

• Strong commercial Java development experience, including multi-threading and network programming.


• Excellent knowledge of JAIN SLEE and SIP Servlet frameworks.


• Proven experience with SIP, RTP/RTCP and SDP protocols.


• Hands-on experience with FreeSWITCH and/or Asterisk.


• Experience integrating cloud-based speech services and AI technologies.


• Exposure to AWS, Microsoft Azure, and Google Cloud Platform environments.


• Strong troubleshooting skills using tools such as Wireshark or sngrep.

Desirable Skills

• Experience with Metaswitch Rhino SLEE or Oracle OCCAS.


• Knowledge of Docker and Kubernetes.


• Understanding of WebRTC, TLS, and SRTP security standards.