SLC

A premium, high-performance communication suite providing secure, real-time messaging, high-fidelity video conferencing, and VOIP-to-PSTN 'World Calls'.

SECURE COMMUNICATIONCase Study
UI/UX CASE STUDYREAL-TIME ARCHITECTUREHYBRID SERVERLESS

Technologies Used

React Native (Expo)FirebaseGetStreamTwilioNode.jsZustand

Technical Architecture & Design Document

1. Overall Project Details

Project SLC is a premium, high-performance communication suite designed to provide secure, real-time connectivity across mobile platforms. It serves as a unified ecosystem for instant messaging, high-fidelity video conferencing, and "World Calls"—a specialized integration that bridges digital VOIP with traditional PSTN (Public Switched Telephone Network) lines. By leveraging a distributed serverless architecture, SLC ensures sub-100ms latency for messaging while providing enterprise-grade security and a credit-based global calling system.

2. Target Audience

  • Privacy-Conscious Individuals: Users seeking a secure, encrypted alternative to mainstream messaging apps for personal data protection.
  • Global Travelers & Expats: Individuals needing a reliable, low-cost way to call international phone numbers (PSTN) directly from a mobile app.
  • Small to Mid-Sized Teams: Organizations requiring a private, branded communication tool for internal chat and video coordination without the overhead of enterprise bloat.

3. User Experience & Workflow

The platform is built around a "Connectivity First" philosophy, ensuring that users can transition from a simple text chat to a high-definition video call or a global phone call with a single tap.

User Journey Flowchart

Interactive Technical Blueprint

4. Technical Architecture Flow

Project SLC utilizes a Hybrid Serverless Architecture. The frontend manages the heavy lifting of media rendering and real-time state synchronization, while the backend is orchestrated through Firebase Cloud Functions and specialized communication providers.

System Architecture

Interactive Technical Blueprint

5. Developer Role & Implementation Focus

  • Real-time Synchronization: Implementing Firebase RTDB for instantaneous messaging, typing indicators, and online presence tracking.
  • High-Fidelity Media: Orchestrating GetStream and Twilio SDKs to handle adaptive bitrate video and crystal-clear audio conferencing.
  • Secure Billing Logic: Developing robust Firebase Cloud Functions to handle PSTN call initiation and atomic credit deductions.
  • Push Notification Pipeline: Engineering a dual-path notification system (Expo + Direct FCM) to ensure message delivery in background states.

6. Technology Stack & Tools Used

  • Frontend: React Native (v0.81), Expo (v54), TypeScript, Zustand
  • Backend: Node.js (Firebase Cloud Functions), Firebase Realtime DB, Firestore
  • Video/Voice: GetStream Video SDK, Twilio Voice/Video SDK
  • Identity & Push: Firebase Auth, Google Cloud Translation, FCM

7. Communication Structure (RTDB & Cloud Functions)

The platform ensures a fluid experience by using Realtime Database for UI-facing events and Cloud Functions for complex backend orchestration.

PSTN Call Execution Flow

Interactive Technical Blueprint