Cloud Virtual PBX (VoIP SaaS) Development for Business(NDA)
TelecomCase study of a high-load VoIP SaaS virtual PBX platform developed for a telecom operator: IVR, call routing, WebRTC, AI modules, and API integrations for enterprise telephony.
About the Project
Telecom • Web, iOS, Android • Cloud Telephony System (Virtual PBX / SaaS)
A regional telecom provider approached our team with a request to develop and integrate a virtual PBX solution for its corporate customers.
The goal was to expand the company’s B2B service portfolio with a cloud-based platform delivering enterprise telephony under a SaaS (Software as a Service) model. The system had to allow client companies to activate and manage virtual PBX services directly from a browser or mobile application, without installing intermediary software.
Project Goals
- Build a high-load distributed enterprise telephony system based on VoIP
- Ensure stable 24/7 operation with fault tolerance and horizontal scalability
- Deliver a flexible interface for managing calls, schedules, restrictions, contacts, and analytics
- Develop cross-platform clients for Web, iOS, and Android with a unified UX/UI
- Meet telecom and personal data regulatory requirements
Solution
We developed an enterprise-grade virtual PBX powered by VoIP (Voice over IP) technology to provide modern digital telephony for businesses.
The platform was built on a microservices architecture using the NATS Jetstream message bus, capable of processing up to 200,000 messages per second. This approach enabled high performance, horizontal scalability, and fault tolerance across the system.
Core Platform Capabilities
- Management of users, numbers, and groups through an admin panel
- Flexible call routing by region, priority, and time schedules
- Interactive voice response (IVR) and call acceptance schedules
- AI-powered call quality monitoring and conversation analysis
- CRM integrations via API and prebuilt connection templates
- Auto-dialing, call recording, and call analytics mechanisms
- Built-in softphone in web and mobile applications via WebRTC
- Support for SIP, conferencing, and multimedia communication channels
Architecture & Technologies
The virtual PBX architecture is based on a modular microservices model with a Backend for Frontend (BFF) layer for each client application. The system includes independent API gateways, providing flexibility, fault tolerance, and straightforward scaling.
Key Components:
- •Asterisk + RtpProxy / PjSIP / WebRTC — IP telephony management
- •NATS Jetstream — message broker and data bus
- •Redis — caching and temporary data processing
- •Zabbix + OpenSearch Stack (Logstash, Kibana, OpenSearch) — monitoring and logging
- •AI modules: Vosk (speech recognition), Dostoevsky (call sentiment analysis)
Technology Stack
Frontend
Backend
Mobile
VoIP
Infrastructure
Team
The project involved 13 specialists:
The project followed an iterative development model with continuous feedback from the client’s technical team. We used an Agile approach and milestone-based prototype demonstrations to keep delivery aligned with business needs.
Implementation Stages
Research and Audit
Review of the existing groundwork created by the previous team
Architecture Design
And preparation of technical specifications based on business requirements
Core Platform and Microservices Development
For telephony and call management
UI/UX and Client Applications Development
Web, iOS, Android
Integration with IP Telephony, CRM, and VoIP Infrastructure
On the client side
Testing, Optimization, and Pilot Launch
Support and Scaling
In production
Results
A fully functional virtual PBX platform was delivered
At enterprise level in 11 months
24/7 system availability was ensured
With high fault tolerance
Routing, auto-dialing, analytics, and quality control tools were implemented
As part of the core telephony workflow
The platform was successfully scaled
For dozens of client companies
Telecom service quality improved
And the operator strengthened its B2B offering
Key Advantages
Summary
This virtual PBX project became a large-scale example of telecom infrastructure digital transformation. The solution enabled the client to offer its corporate customers a modern, flexible, and secure communication service that combines the simplicity of the SaaS model with the power of VoIP technologies.
Want to discuss your project?
Get in touch, and we’ll show you how we can help bring your idea to life