Senior FreeSWITCH / VoIP Engineer (SIP, WebRTC, ESL)

Job Summary

We are looking for a FreeSWITCH Implementation Engineer who will be responsible for designing, deploying, configuring, integrating, and maintaining FreeSWITCH-based VoIP platforms. The role involves working closely with SIP, RTP, WebRTC, IVR, conferencing, call routing, and external integrations in a production environment.

Key Responsibilities

FreeSWITCH Core Responsibilities

Install, configure, and maintain FreeSWITCH in production environments from the scratch.

Design and implement call flows, dialplans, IVRs, conferencing, and call routing with complete ownership.

Configure SIP profiles (internal/external), gateways, trunks, and extensions

Implement multi-tenant and high-availability FreeSWITCH architectures

SIP, RTP & Networking

Strong understanding of SIP signaling, RTP media, and SDP negotiation

Troubleshoot one-way audio, no-audio, call drops, registration failures

Configure NAT traversal, firewall rules, and RTP port ranges

Analyze SIP logs and traces (siptrace, sngrep, tcpdump)

Dialplan & Scripting

Develop dialplans using:

XML

Lua / JavaScript / Python

Implement logic for:

Call queues for inbound and outbound calls

Time-based routing

Skill-based routing

Failover and fallback handling

Integrations & APIs

Integrate FreeSWITCH with:

CRM / ERP systems

Billing platforms

AI voice bots (ASR/TTS)

External WebSocket or REST services

Use Event Socket Library (ESL):

Inbound & Outbound ESL

Real-time call control and monitoring

WebRTC & Media

Configure WebRTC support (DTLS-SRTP, ICE, OPUS)

Work with mod_verto, SIP over WSS

Implement browser-based calling solutions

Monitoring & Debugging

Monitor system performance and call quality

Analyze logs and CDRs

Optimize codec usage and RTP performance

Handle live production incidents and RCA

Deployment & Operations

Deploy FreeSWITCH on:

Linux (CentOS / Ubuntu)

Cloud platforms (AWS / GCP / Azure – preferred)

Configure HA, load balancing, and scaling

Work with DevOps teams for CI/CD, backups, and automation

Required Skills

Technical Skills

Strong experience with FreeSWITCH

Solid knowledge of VoIP protocols (SIP, RTP, RTCP, WebRTC)

Linux system administration

Dialplan development (XML/Lua/JS/Python)

ESL & event-driven call control

Debugging tools (fs_cli, sngrep, tcpdump)

SQL / MySQL / PostgreSQL (CDR, reporting)