The open-source unified cmmunication ecosystem has matured dramatically in telecom infrastructure. VoIP switching, routing, and SIP signaling have been battle-tested for years. But billing? Billing is where operations either scale… or collapse under unbilled CDRs and revenue leakage.

In 2026, VoIP billing systems are no longer just about rating calls. Modern providers demand:

• Real-time billing and balance control
• Wholesale and retail support in one platform
• Multi-tenant reseller hierarchies
• API-first integration with CRM, ERP, and payment gateways
• Fraud detection and revenue assurance
• High-volume CDR processing
• Scalable architecture ready for cloud-native deployments

Open-source billing platforms remain attractive because they provide:

• No licensing lock-in

• Customization freedom

• Transparent logic

• Community-driven improvements

• Lower operational cost

Below is a comprehensive and updated analysis of the top 5 open-source VoIP billing systems dominating the market in 2026.

1) PyFreeBilling

License: AGPLv3
Core Stack: Kamailio + FreeSWITCH + PostgreSQL
Best For: Wholesale carriers and high-volume operators

Overview

PyFreeBilling remains one of the most technically modern open-source VoIP billing engines available. Unlike older PHP-based panels, this system was built with scalability in mind.

It is commonly deployed in wholesale carrier environments where millions of CDRs are processed daily. If you are operating at serious scale, this platform understands your pain.

Architecture Strength

• Asynchronous processing model
• PostgreSQL-based robust CDR storage
• Worker-based architecture for large call loads
• API-driven management

It integrates naturally with Kamailio and FreeSWITCH, making it ideal for SIP routing environments that prioritize performance.

Core Features

• Real-time billing and rating
• Least Cost Routing (LCR) engine
• Advanced rate table management
• Bulk rate import/export
• Fraud detection mechanisms
• REST API integration
• Radius compatibility
• Wholesale margin management

Scalability

PyFreeBilling handles high concurrency environments well because of its database design and processing logic. Horizontal scaling with proper PostgreSQL tuning makes it suitable for carrier-grade deployments.

Strengths

• Modern architecture
• High CDR throughput
• Designed for wholesale telecom
• API-first structure

Limitations

• Requires experienced DevOps handling
• Not beginner-friendly for small startups

2) ASTPP (A Smart TelePhony Platform)

License: Open Source + Commercial Extensions
Core Stack: FreeSWITCH + MongoDB/MySQL + Redis
Best For: ITSPs, startups, and multi-tenant providers

Overview

ASTPP is more than billing software. It’s a telephony platform ecosystem that combines routing, rating, DID management, and customer control panels.

Its modular approach makes it attractive to service providers who want a full stack in one place.

Core Features

• Real-time dynamic rating
• Multi-tenant billing
• Taxation rules
• LCR and failover routing
• DID inventory management
• Reseller hierarchy
• Customer and admin dashboards
• WebRTC support
• JSON/REST APIs

Multi-Tenant Capabilities

ASTPP shines in multi-tenant environments. It supports:

• ACL-based access control
• Reseller chains
• Customer-level pricing
• Per-tenant rate control

Performance and Scaling

Redis caching and FreeSWITCH integration allow relatively strong performance. While not as pure-carrier focused as PyFreeBilling, it is extremely versatile.

Strengths

• Complete ecosystem
• Strong UI
• Flexible rating models
• Good documentation

Limitations

• Some advanced features require commercial add-ons
• Can feel heavy for minimal setups

3) MagnusBilling

License: GPLv3
Core Stack: Asterisk + MariaDB + PHP
Best For: Regional operators and SIP trunk providers

Overview

MagnusBilling continues to be one of the most deployed open-source billing solutions for Asterisk-based systems. It is mature, stable, and practical.

It may not be cutting-edge in architecture, but reliability matters more than fashion in telecom.

Core Features

• Real-time billing
• Multi-level reseller system
• Customer dashboards
• SMS and DID support
• Rate tables and routing logic
• Margin calculation (buy/sell rates)
• Call monitoring
• API integration

Deployment Use Cases

• SIP trunk providers
• VoIP resellers
• Calling card businesses
• Regional ITSPs

Strengths

• Large installation base
• Familiar Asterisk integration
• Feature-rich panel
• Good reporting capabilities

Limitations

• PHP-based architecture
• Not ideal for very large wholesale carriers

4) A2Billing (Community-Driven Forks)

License: GPLv2
Core Stack: Asterisk + MySQL
Best For: Calling card providers and prepaid VoIP

Overview

A2Billing is the veteran in this space. While official updates slowed down years ago, community forks remain active and usable in 2026.

Its strength lies in simplicity and familiarity.

Core Features

• Prepaid and postpaid billing
• Multi-currency
• Multilingual interface
• Agent and reseller management
• Payment gateway integration
• CDR reporting and invoices

Where It Still Fits

• Small VoIP startups
• Calling card deployments
• Budget-focused providers

Strengths

• Lightweight
• Easy deployment
• Strong Asterisk integration

Limitations

• Aging architecture
• Limited modern API support

5) CDR-Stats

License: BSD
Core Stack: Django + PostgreSQL + Celery
Best For: Analytics, reporting, auditing

Overview

CDR-Stats is not a full billing engine, and that’s exactly why it deserves attention. Modern telecom operations rely heavily on analytics, compliance, and revenue assurance.

This platform aggregates CDRs across systems and provides deep reporting capabilities.

Core Features

• Centralized CDR ingestion
• Rating for analysis
• Dashboard visualization
• Historical trends
• PDF/CSV reporting
• Alerts and monitoring
• Multi-provider support

Strategic Importance

Billing errors are expensive. CDR-Stats helps detect:

• Margin mismatches
• Routing anomalies
• Fraud patterns
• Carrier cost discrepancies

Strengths

• Excellent reporting
• Django-based modern stack
• Scalable architecture

Limitations

• Requires pairing with the billing engine

Feature Comparison Overview (Strategic View)

Industry Trends in 2026

1) Real-Time Rating Is Mandatory

Delayed billing models are risky. Real-time balance control is now expected.

2) API-First Ecosystems

Modern VoIP businesses integrate billing with:

• CRM systems
• Payment gateways
• Unified Communication platforms
• Automation scripts

3) Revenue Assurance & Fraud Detection

Telecom fraud continues evolving. Billing platforms must include:

• Traffic anomaly detection
• Spending limits
• Auto-block triggers

4) Multi-Currency & Global Expansion

Providers operate across borders. Systems must support:

• Currency conversion
• Taxation logic
• Regional pricing models

How to Choose the Right Platform

If You Are a Wholesale Carrier

Choose PyFreeBilling.

If You Want an All-in-One VoIP Platform

Choose ASTPP.

If You Run Asterisk and Want Stability

Choose MagnusBilling.

If You Run Calling Cards or Small Prepaid Business

Choose A2Billing.

If You Need Deep Reporting & Auditing

Add CDR-Stats alongside your billing engine.

Conclusion

The open-source VoIP billing ecosystem in 2026 remains powerful, diverse, and relevant. While commercial telecom billing suites exist, open-source solutions continue to offer flexibility, transparency, and customization freedom that many operators prefer.

Each system discussed here serves a different segment of the telecom market. The key is aligning:

• Your traffic volume
• Your business model
• Your technical expertise
• Your scaling roadmap

Choose correctly, and billing becomes an asset. Choose poorly, and you’ll spend nights chasing CDR mismatches instead of growing your network.

Telecom is ruthless about inefficiency. Your billing system cannot be.