KK
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Web Client & PBX Backend

Projects

3CX

PBX

Key ContributorProduction

Stack

  • TypeScript
  • Angular
  • Vue
  • React / Next.js
  • RxJS
  • C#
  • .NET
  • Node.js
  • WebRTC
  • WebSockets
  • VoIP / SIP
  • REST
  • Voice AI
  • MCP

Overview

Enterprise VoIP PBX and unified communications platform serving 350k+ organizations globally. Contributed across real-time communications, web client architecture, LiveChat, AI-powered voice agents, and telephony integrations, with a focus on performance, scalability, and conversational AI.

Technical Challenges

A PBX web client has to stay consistent under high load: live call state across WebRTC sessions, heterogeneous data sources, CRM and VoIP provider integrations — all while the UI stays responsive and state doesn't drift.

My Contributions

Web Client & PBX Backend

3CX's core product — enterprise PBX and unified communications platform serving 350k+ organizations. I ship features end to end across the WebClient and platform backend.

  • Built the UI, configuration workflows, and PBX-level integration for the 3CX AI Voice Agents — extended the user model with impersonation, enabled AI-driven call flows and RAG, and delivered full-stack integrations with various AI providers.
  • Re-architected RxJS pipelines and core client services for call-state synchronization, reducing median latency from ~250ms to ~120ms across heterogeneous data sources without state drift.
  • Migrated the PBX WebClient from AngularJS to Angular v20.
  • Contributed to a large-scale WebClient redesign by owning real-time services — dialer, call panels, and in-call surfaces.
Web Client & PBX Backend
Web Client & PBX Backend

Call Control Web API

Programmatic API for controlling live calls and call flows on 3CX — enables third-party apps to handle, route, and automate telephony on the platform, with access to live voice streams.

  • Built a set of third-party reference applications for call flow automation — Programmable IVR, Outbound Campaigns, ERP Call Preprocessor, and more — using the Call Control API to handle inbound calls, process customer context before agent transfer, or run conditional outbound campaigns.
  • Developed 3CX's first AI voice agent for evaluating and transferring calls via Call Control — the initiative that sparked the company's broader AI integration.
  • Shipped a production Call Control API application for the China team on Qwen Realtime, designed around regional AI service availability and restrictions.
  • Based on these solutions and Call Control API experience, prototyped Voice Agent Orchestrator, a provider-agnostic AI runtime for building and operating voice agents on telephony.

LiveChat

Embeddable Vue 3 web component for live chat and calls — injectable on any website via snippet, with CMS plugins and custom integrations. Primary maintainer of the component.

  • Migrated LiveChat from Vue 2 to Vue 3 — modernized the build and test stack, overhauled legacy dependencies, and mitigated security vulnerabilities.
  • Developed injection plugins for dozens of CMS platforms, contributing to 150k+ active installations across CMS and e-commerce sites.
  • Currently working on the next version with an updated design and AI features.
LiveChat
LiveChat
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