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Quo

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Business Communications Platform

From YC startup to $105M platform. Built on the right foundation.

OpenPhone set out to replace the business phone system for modern teams. To get there, they needed a senior engineering partner to build the cross-platform infrastructure from the ground up.

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Client Overview

The business phone system built for how teams actually communicate.

Quo — formerly OpenPhone — is the AI-powered business phone platform trusted by over 20,000 companies worldwide. Founded in 2018 and backed by Y Combinator, it combines calls, texts, voicemail, and a lightweight CRM into a single collaborative workspace available on iOS, Android, Mac, Windows, and Web.

 

Starting with a small team and a clear vision, OpenPhone grew from a YC S18 startup into a platform that has raised $105M and processes millions of calls and messages every month.

20,000+

Companies

$105M

Raised

The challenge

Building a reliable, real-time communications platform from scratch meant solving hard technical problems across every layer of the stack.

01

Cross-Platform Consistency

Delivering a seamless, native-quality experience across iOS, Android, Mac, Windows, and Web without fragmenting the codebase or multiplying maintenance overhead.

02

Real-Time Communication at Scale

Handling live calls, SMS, and voicemail with the reliability and latency expectations of a business-grade phone system for thousands of concurrent users.

03

VoIP Infrastructure Complexity

Integrating Twilio and SIP protocols into a product that needed to behave like a native phone, not a third-party integration -- stable, fast, and transparent to the end user.

04

Scalability from Day One

Designing the backend architecture to handle growth from early-stage users to tens of thousands of companies without requiring a full rebuild at each inflection point.

05

Security and Compliance

Protecting business communication data with enterprise-grade access control, encryption, and audit trails without slowing down a startup moving at speed.

The solution

Nearshore Innovation for Scalable Impact

Vanguard X assigned a dedicated team of senior engineers, mobile specialists, and DevOps experts to own the full stack. From architecture decisions to production deployment, the team operated as an extension of OpenPhone from day one.

Web Application

  • Built the React and Redux web app with real-time messaging, VoIP controls, and contact management across all major browsers.
  • Implemented live call state management and notification systems for seamless in-browser communication.
  • Optimized frontend performance to maintain sub-second load times under growing user load.

Mobile App (iOS + Android)

  • Developed the cross-platform mobile app in React Native with native module integrations for audio, push notifications, and background call handling.
  • Built offline support and sync logic so the app remained functional in low-connectivity environments.
  • Maintained platform parity between iOS and Android to reduce QA overhead and ship updates simultaneously.

Backend & Telephony

  • Built the Node.js and GraphQL API layer handling authentication, messaging, call routing, and contact sync.
  • Integrated Twilio SDKs and custom SIP logic to power reliable VoIP calling with failover handling.
  • Designed the PostgreSQL data model for multi-user shared inboxes, call history, and CRM-lite functionality.

DevOps & Monitoring

  • Set up CI/CD pipelines with GitHub Actions and Docker on AWS ECS for fast, low-risk deployments.
  • Configured Sentry, Datadog, and CloudWatch for real-time error tracking and infrastructure observability.
  • Implemented environment isolation and access controls to protect customer communication data at every layer.

Impact & Results

The hardest part of scaling a communications platform isn't the features. It's the infrastructure. They got that immediately."

99,9%

Platform Uptime

The platform maintained near-perfect reliability processing millions of calls and messages monthly under production load.

10M+

Monthly Interactions

Calls and messages processed every month across iOS, Android, and web without performance degradation.

30%

Faster Time-to-Market

Automated CI/CD pipelines cut feature delivery time, letting the team ship faster without increasing risk.

$105M

Raised Post-Engagement

From YC S18 startup to a $105M platform. Built on the infrastructure Vanguard X helped lay from day one.

We Used Advance TECHNOLOGY

Our engineers bring deep expertise in the most in-demand technologies, frameworks, and programming languages.

Python LLM RAG Machine Learning PyTorch TensorFlow LangChain OpenAI API Anthropic API Cursor GitHub Copilot Claude Code Node.js NestJS React Next.js TypeScript Java Go NET / .NET Core C#
Python LLM RAG Machine Learning PyTorch TensorFlow LangChain OpenAI API Anthropic API Cursor GitHub Copilot Claude Code Node.js NestJS React Next.js TypeScript Java Go NET / .NET Core C#
Ruby on Rails Express Rust PHP JavaScript Angular Vue.js AWS GCP Azure Kubernetes Docker Terraform Serverless Microservices ETL Spark Kafka Snowflake Databricks Airflow Kotlin React Native Flutter iOS Android Selenium Cypress Cucumber Jenkins
Ruby on Rails Express Rust PHP JavaScript Angular Vue.js AWS GCP Azure Kubernetes Docker Terraform Serverless Microservices ETL Spark Kafka Snowflake Databricks Airflow Kotlin React Native Flutter iOS Android Selenium Cypress Cucumber Jenkins

Why choose Vanguard-X

OpenPhone needed a team that could own the full stack and ship at startup speed, without compromising the foundation.

Engineer retention rate

94%

Avg. engineer tenure

2.8 yrs

Fully operational

5 days

OpenPhone needed more than developers. They needed a team that could own the full stack, make architectural decisions independently, and ship at startup speed without cutting corners on infrastructure.

 

Vanguard X provided senior engineers with deep VoIP and mobile expertise who integrated from day one and built a foundation ready to scale.

OpenPhone didn’t just need code written. They needed a team that could think product-first and build for scale before scale arrived.

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