Job Overview
We're looking for a Free SWITCH Developer to build and scale real-time communication platforms, with a robust focus on Web RTC and Web Socket-based calling. You'll design XML dialplans and call flows, build integrations over ESL, debug SIP and media problems across browser and SIP endpoints, and take ownership of how the telephony layer scales in production.
Key Responsibilities
Design, configure, develop, and maintain Free SWITCH platforms. Build and maintain XML dialplans, gateways, SIP profiles, extensions, and call-routing logic. Implement and scale Web RTC calling — SIP over Web Socket (WSS), DTLS-SRTP, ICE/STUN/TURN, Opus/VP8, browser-to-PSTN and browser-to-browser flows. Work with Js SIP/SIP.js and other Web RTC/SIP clients; support the frontend team on client-side call integration. Develop integrations using ESL (inbound and outbound event socket), mod_xml_curl, REST APIs, and Web Sockets. Configure and troubleshoot SIP trunks, endpoints, DID/DDI routing, caller ID/CLI, and number translation. Diagnose SIP signalling and media issues — one-way audio, no audio,



call drops, registration and NAT failures, ICE failures, codec and transcoding problems — using Sofia logs, PCAPs, Wireshark, and tcpdump. Integrate Free SWITCH with CRMs, databases, third-party APIs, and AI/voice platforms (ASR, TTS, LLM-driven voice agents) via mod_audio_stream / Web Socket media streaming. Implement call recording, CDR, billing hooks, call-detail processing, and reporting. Own scaling of the telephony layer: multi-node Free SWITCH deployments, media/signalling separation, TURN server capacity, failover, and safe rolling deploys. Work with the infrastructure team on sizing, networking, firewall and media port configuration, and deployment topology. Handle production incidents and lead root-cause analysis. Write and maintain technical documentation for call flows, configurations, and troubleshooting runbooks. Required Skills
Free SWITCH (deep)
3+ years hands-on Free SWITC

📌 Freeswitch developer (Bengaluru)
🏢 CC33 Global
📍 Bengaluru