Embedded Linux & VoIP Software Engineer

General Devices is seeking a FreeSWITCH / VoIP Software Engineer to develop, maintain, and enhance its SIP-based communication platform and embedded Linux devices. The role focuses on FreeSWITCH development, SIP/RTP networking, embedded Linux integration, hardware bring-up, and real-time audio, in collaboration with cross-functional engineering teams.

Responsibilities:

• FreeSWITCH Dialplans - Design, extend, and troubleshoot the FreeSWITCH XML dialplans generated from configuration by our C#/.NET SIP Service, including conditions, actions, channel variables, call routing, and call-flow control
• Conference Engine - Maintain mod_conference configurations and behavior, including participant management, conference controls, and one-to-many audio distribution
• SIP Service Integration - Extend and troubleshoot our Windows-hosted C#/.NET SIP Service built on FreeSWITCH, using ESL, FreeSWITCH APIs, events, and scripting
• SIP/RTP Communications - Handle SIP endpoints, registration, routing, media sessions, signaling, interoperability, and call-quality issues
• Embedded Linux - Develop and maintain the C#/.NET applications on our ARM-based Buildroot Linux devices, including their vendor C SDK integration, and the Buildroot images themselves; support system services, deployment, releases, updates, and recovery
• Hardware Bring Up - Bring up new boards with our hardware engineer: device trees, U-Boot, kernel drivers and peripherals (I2C, GPIO, SPI, UART, McASP/TDM audio, Ethernet)
• Real-time Audio - Investigate ALSA, RTP, buffering, jitter, latency, echo, and end-to-end audio quality
• System Integration - Collaborate with hardware, backend, frontend, and QA engineers; support radio and telephone interfaces including PTT and related signaling
• Debugging & Delivery - Use FreeSWITCH CLI/logs, SIP traces, Wireshark, tcpdump, and audio captures; maintain code, CI, tests, and documentation

Requirements:

• Practical development and troubleshooting experience with FreeSWITCH, particularly XML dialplans and conference functionality (mod_conference)
• Solid understanding of SIP, RTP, TCP/IP, UDP, call flows, and packet-level troubleshooting
• Experience developing, deploying, and debugging software on embedded Linux on ARM (Buildroot or Yocto)
• Proficiency in C, C++, or C#, with willingness to work in the languages used here (C#/.NET and C), and ability to work with an existing multi-language codebase
• Approximately 3+ years of relevant professional development experience; demonstrated capability matters more than a rigid year count
• Strong learning ability, ownership, collaborative communication, and systematic problem-solving
• Event Socket Library (ESL), Lua scripting, FreeSWITCH APIs, SIP profiles, and complex conference workflows
• C#/.NET, Windows services, native C SDK integration, and Angular/TypeScript
• TI Sitara AM335x and AM625 (AM62x family); U-Boot, device trees, kernel configuration, and peripheral interfaces
• ALSA, TDM, real-time audio, two-way radio, dispatch/public-safety communications, analog telephony, PTT, COR, and tone signaling
• Git, GitLab CI, Jira, Confluence, Docker, AWS, and effective use of AI-assisted development tools