01 / Telecom

2024—NOW

Infrastructure
behind ~1M users.

Backend services for eSIM, phone number provisioning, call routing and VPN.

Role
Full Stack Engineer
Company
Kevych Solutions
Tech
Node.js / NestJS / SIP / VoIP / PostgreSQL / Redis

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01

Overview

A telecom platform serving approximately one million users, covering eSIM and phone-number provisioning, call routing and VPN.

I architected and shipped its Node.js and NestJS services, integrated SIP/VoIP providers for real-time call handling, and built the self-service tooling business customers use to manage accounts, provisioning and usage.

02

The problem

Four capabilities had to work in production for a user base of roughly one million.

  • Provisioning: eSIM profiles and phone numbers for subscribers.
  • Call routing: connecting calls in real time through SIP/VoIP providers.
  • VPN: a VPN service delivered alongside the telecom offer.
  • Self-service: business customers managing accounts, provisioning and usage without going through operations.

03

System

Node.js and NestJS services sit between the subscriber-facing products and the carrier-side providers.

  1. Clients

    • Subscribers (~1M)
    • Business customers · self-service tooling

  2. Services · Node.js / NestJS

    • eSIM provisioning
    • Number provisioning
    • Call routing
    • VPN

  3. Providers

    • SIP / VoIP providers

  4. Data

    • PostgreSQL
    • Redis

04

What I built

  • Architected the Node.js/NestJS services for eSIM and phone-number provisioning, call routing and VPN, and shipped them to production.
  • Integrated SIP/VoIP providers for real-time call handling.
  • Built self-service tooling for business customers covering accounts, provisioning and usage.

05

Engineering decisions

Services on NestJS
Provisioning, call routing and VPN are built as Node.js/NestJS services.
Calls through SIP/VoIP providers
Real-time call handling integrates external SIP/VoIP providers.
Self-service for business customers
Business customers manage accounts, provisioning and usage themselves through dedicated tooling.

06

Impact

~1M users

  • Provisioning, call-routing and VPN services in production for a platform serving approximately one million users.
  • Business customers manage accounts, provisioning and usage through self-service tooling.
  • Ongoing since 2024.

07

Stack

  • Node.js
  • TypeScript
  • NestJS
  • PostgreSQL
  • Redis
  • SIP / VoIP