Software Engineer III – VoIP / FreeSWITCH

We're looking for an experienced FreeSWITCH Developer / VoIP Software Engineer to design, develop, and maintain the telephony solutions that power Vonage's call processing platform. You'll build real-time voice communication systems that handle millions of calls, developing features like call processing, recording, voicemail, conferencing, and external service integrations. This is a critical role where your work directly impacts business communications for customers worldwide.

What You'll Do

Core Responsibilities

• Build scalable telephony systems — Design and develop distributed, high-volume production telephony applications for our UCaaS platform that handle real-time voice traffic at scale
• Develop custom FreeSWITCH solutions — Create custom modules, dialplan configurations, and ESL (Event Socket Library) integrations for advanced call control and automation
• Deliver advanced telephony features — Implement call recording, voicemail transcription, fax processing, audio streaming, and other mission-critical voice features
• Rapid prototyping to production — Build proof-of-concepts quickly and evolve them into production-ready, maintainable code
• Drive technical innovation — Evaluate emerging telephony technologies and recommend architectural improvements that enhance our platform capabilities
• Mentor and lead — Guide team members on design patterns, best practices, and telephony architecture decisions

Day-to-Day Collaboration

• Participate in the full agile development lifecycle: sprint planning, design reviews, standups, and demos
• Respond promptly to production incidents affecting customers and business operations
• Work independently on end-to-end feature delivery while contributing to broader team goals
• Partner closely with Product Management, QA, and Operations teams to deliver cohesive solutions
• Communicate progress, blockers, and technical decisions clearly with engineering leadership

What You'll Bring

Required Experience & Skills

Telephony & VoIP Expertise (Must-Have)

• 6+ years of software development experience
• 3+ years hands-on experience with telephony platforms: FreeSWITCH, Asterisk, or similar open-source PBX systems
• Deep understanding of:
• SIP (Session Initiation Protocol) and RTP protocols
• VoIP architecture and NAT traversal techniques (STUN, ICE, TURN)
• Audio codecs (G.711, Opus, etc.)
• Dialplan development and call flow design

Programming & Development

• Strong proficiency in Java, C/C++, Python, and SQL
• Experience with CI/CD pipelines and modern development workflows
• Infrastructure as Code practices
• Containerization with Docker and Kubernetes

Cloud & Infrastructure

• Hands-on experience with AWS services: EC2, EKS, Lambda, S3, SNS, SQS, CloudFront
• Linux systems expertise: performance tuning, networking, file systems
• Database experience with:
• Relational: MySQL, PostgreSQL
• NoSQL: Redis, MongoDB

Problem-Solving & Debugging