Software Developer

Rubicon Consulting; Greater London; On-site; GBP 70,000 - 90,000; Full time

Job summary

Rubicon Consulting is seeking a Voice Services Developer on a 4+ year contract based in Suffolk. You will build, maintain, and optimize SIP-based voice services, bridging traditional telephony and cloud-based AI.

Focus areas include Java development, SIP/VoIP, and integration of Speech AI across multi-cloud environments. Responsibilities include developing, testing, and scaling SIP services, managing FreeSWITCH/Asterisk engines, and deploying applications across AWS, Azure, and Google Cloud.

Qualifications

• Proficient in Java with multi-threading and network programming.
• Strong knowledge of JAIN SLEE and SIP Servlet Frameworks.
• Hands-on experience with FreeSWITCH or Asterisk telephony engines.
• Solid understanding of SIP, RTP/RTCP, and SDP.
• Experience integrating cloud Speech APIs (e.g., AWS/Azure/Google) for Speech AI.

Responsibilities

• Develop, test, and maintain SIP-based voice services.
• Configure and scale FreeSWITCH or Asterisk engines.
• Integrate Speech-to-Text and Text-to-Speech workflows.
• Deploy and monitor voice apps across AWS, Azure and GCP.
• Troubleshoot audio quality, call drops, and latency issues.
• Collaborate with senior architects and DevOps teams to rollout scalable conversational AI bots.

Skills

Java

SIP/VoIP knowledge

Multi-threading

Network programming

Speech AI concepts

Tools

Wireshark

sngrep

FreeSWITCH

Asterisk

JAIN SLEE

SIP Servlet Frameworks

Docker

Kubernetes

Job description

Rubicon Consulting is currently recruiting for a Software Developer on a 4+ year contract based in Suffolk.

Role Summary

We are seeking a Voice Services Developer to build, maintain, and optimize our next-generation communication platforms. You will bridge the gap between traditional telecommunication protocols and modern cloud-based AI. Your core focus will be developing stable SIP services using Java, managing open-source media engines, and integrating advanced Speech AI technologies across multi-cloud environments.

Key Responsibilities

• SIP Development: Develop, test, and maintain mid-to-high performance SIP-based voice services using JAIN SLEE, SIP Servlets.
• Media Server Administration: Configure, manage, and scale FreeSWITCH or Asterisk communication engines.
• Speech AI Integration: Implement Speech-to-Text (STT), Text-to-Speech (TTS), and Natural Language Processing (NLP) workflows into live voice streams.
• Cloud Operations: Deploy and monitor voice applications across AWS, Azure, and Google Cloud Platform (GCP).
• Troubleshooting: Use network analysis tools to diagnose audio quality issues, call drops, and latency problems.
• Team Collaboration: Work alongside senior architects and DevOps teams to roll out scalable conversational AI bots.

Requirements

• Core Language: Professional experience with Java, including multi-threading and network programming.
• In depth knowledge of Java
• Good knowledge of java applications using JAIN SLEE framework, SIP Servlet Frameworks
• Telephony Engines: Hands-on experience configuring and scripting with FreeSWITCH or Asterisk.
• Voice Protocols: Solid understanding of SIP, RTP/RTCP, and SDP.
• Speech AI: Experience integrating cloud speech APIs (e.g., AWS Transcribe/Polly, Azure Speech, Google Cloud Speech-to-Text).
• Multi-Cloud Exposure: Experience deploying and managing applications on AWS, Azure, and GCP.
• Tools: Proficiency with Wireshark or sngrep for VoIP troubleshooting.

Preferred Qualifications

• Experience with Java telephony frameworks like Metaswitch Rhino SLEE or Oracle OCCAS.
• Understanding of containerisation using Docker and Kubernetes in cloud environments.
• Knowledge of WebRTC and telephony security standards like TLS and SRTP.

Our Company

Rubicon Consulting is a Talent management consultancy which helps you to optimise business performance and competitive advantage by choosing the right people first time