Cymetrix Software - SIP Developer - PBX System

Responsibilities :

• Design and implement telephony integrations using SIP and SIPREC.
• Develop APIs and backend services to handle call control, call recording, and session management.
• Work with PBX systems, SIP Servers, and Media Servers for SIP call flows and media capture.
• Integrate third-party VoIP systems with internal applications and platforms.
• Analyze and troubleshoot SIP signaling and RTP media flows.
• Collaborate with cross-functional teams including DevOps, Product, and QA to deliver scalable solutions.
• Create technical documentation, diagrams, and support material.
• Ensure systems are secure, resilient, and Skills :
• Strong experience with SIP protocol (INVITE, ACK, BYE, REGISTER, REFER, OPTIONS, etc.).
• Practical experience with SIPREC for recording VoIP calls.
• Solid development skills in JavaScript (Node.js).
• Experience working with SIP Servers (e.g., FreeSWITCH, Asterisk, Kamailio, OpenSIPS).
• Hands-on knowledge of WebRTC, RTP streams, and VoIP media handling.
• Experience building and consuming RESTful APIs.
• Familiarity with call flows, SIP traces analysis (using Wireshark, sngrep, or similar).
• Strong understanding of networking basics (UDP, TCP, NAT traversal, STUN / TURN).
• Ability to troubleshoot and debug complex telephony and media to Have Skills :
• Experience with Media Servers (e.g., Janus, Kurento, Mediasoup).
• Knowledge of Call Recording Systems architecture and compliance standards (PCI-DSS, GDPR).
• Experience with Cloud Telephony Platforms (Twilio, Genesys Cloud, Amazon Chime SDK, etc.).
• Familiarity with Session Border Controllers (SBCs).
• Prior experience with SIP trunking and carrier integrations.
• Exposure to Protocol Buffers or gRPC for real-time messaging.
• Understanding of security practices in VoIP (TLS, SRTP, SIP over WebSockets).
• Knowledge of Docker and Kubernetes for deploying SIP services at scale.
• Sound knowledge of telecom protocols like Shall be thoroughly analytical and fix issues for SBC Portfolio of Products.
• Shall be thorough with Linux / RTOS internals and product Architecture is preferred.
• Strong Knowledge of TCP / UDP / IP and networking concepts is a must.
• Knowledge of IP telephony, SIP, Call Routing Techniques of ARS, AAR on Trunk config environment.
• Prior Experience on working with FreeSwitch, Kamailio & RTP Proxy, etc.
• Strong understanding of Audio streaming / websockets and their application in real-time communication systems.
• In-depth knowledge of audio codecs and their impact on voice quality and bandwidth utilization.
• Experience with gRPC and Protobuf for building efficient and scalable communication interfaces.
• Extensive experience in large scale product development in Enterprise, webRTC, VoIP, VoLTE based Language / Framework :
• Primary Language : JavaScript (Node.js backend).
• Frameworks / Tools : Express.js, Socket.io (for signaling if needed), Wireshark (for debugging), Sngrep.

(ref : hirist.tech)