Sr Software Engineer | Voice

Join us in bringing joy to customer experience.  Five9 is a leading provider of cloud contact center software, bringing the power of cloud innovation to customers worldwide.    Living our values everyday results in our team-first culture and enables us to innovate, grow, and thrive while enjoying the journey together.

We celebrate diversity and foster an inclusive environment, empowering our employees to be their authentic selves.  About Five9 Five9 is a leading provider of cloud contact center solutions, enabling businesses to deliver exceptional customer experiences. Our mission is to ensure reliability, scalability, and innovation in real-time communication systems.

About The Team

The VACS team delivers critical voice call control and AMD (Answering Machine Detection) capabilities for Five9’s global contact center solutions. We focus on 99.999% uptime, robust applications, and real-time communication. Our stack includes Linux, Java, Kotlin, Kafka, and Kafka Connect, interfacing with multiple AMD vendors to optimize resource utilization and customer experience.

Role Purpose As a Senior Software Engineer, you will: Solve complex business problems in the VoIP domain. Implement advanced features and continuously enhance Five9’s call control services. Collaborate across teams to deliver scalable, highly available voice platforms.

Key Responsibilities

Manage operational and tactical aspects of customer service issues and escalations. Implement, troubleshoot, and support Five9 Voice call control & configuration services. Develop software applying performance and scalability principles. Mentor and train junior team members. Communicate plans, progress, and status effectively.

Required Skills & Qualifications 5+ years of software development experience. Strong expertise in Java (8 & 17) and Kotlin. Experience with Spring/Spring Boot, Kafka, Kafka Connect, and Debezium Connectors. Hands-on experience with VoIP technologies and troubleshooting tools. Strong debugging and analytical skills.

Agile/Scrum experience. Bachelor’s degree (or equivalent) in a relevant discipline. Preferred Skills Knowledge of VoIP protocols (SIP, RTP, RTCP, WebRTC). Experience with MySQL/PostgreSQL. Exposure to Contact Center, IVR, Virtual Agents, and telecom service providers.  Five9 embraces diversity and is committed to building a team that represents a variety of backgrounds, perspectives, and skills.

The more inclusive we are, the better we are. Five9 is an equal opportunity employer.  View our privacy policy, including our privacy notice to California residents here: https://www.five9.com/pt-pt/legal.   Note: Five9 will never request that an applicant send money as a prerequisite for commencing employment with Five9.

Five9, Inc., together with its subsidiaries, provides cloud software for contact centers in the United States and internationally. The company offers virtual contact center cloud platform that delivers a suite of applications, which enables the breadth of contact center-related customer service, sales, and marketing functions.

Its solution enables its clients to manage these customer interactions across various channels, including voice, video, chat, email, website, social media, click-to-call,...