A High-Stakes Migration in Telecom Infrastructure

Viettel High Technology Industries Corporation (Viettel High Tech), a key arm of Viettel Group, has completed a massive migration of more than 100 million subscribers and approximately 5,000 tariff plans at Viettel, Vietnam's largest mobile operator, to its in-house cloud-native charging system, vOCS 4.0. This transition, executed on a live national network, was completed within a three-month cutover window with zero downtime and no service disruption.

Replacing an Online Charging System (OCS) is widely regarded as one of the most complex and high-risk operations a telecommunications provider can undertake. Because the OCS acts as the real-time engine for billing, balance management, and service authorization, any failure can lead to immediate revenue loss or widespread service disruption. To mitigate these risks, Viettel High Tech utilized a strategy of real-time data synchronization, parallel running, and a phased cutover, supported by instant rollback capabilities at every stage of the process.

This deployment has earned international recognition, securing the Telecom Review Excellence Awards 2026 prize for Best Technology Deployment in Asia. This marks the first time a Vietnamese company has received this specific accolade.

Technical Architecture and Performance Metrics

The vOCS 4.0 platform introduces several key performance capabilities designed to meet the demands of modern telecommunications networks:

  • Transaction Capacity: The system processes more than 300,000 transactions per second.
  • Latency: Latency is maintained below 5 milliseconds.
  • Network Convergence: The platform supports 2G–5G and fixed services on one platform.
  • Infrastructure Efficiency: By sharing infrastructure directly with the network, the deployment requires up to 50% less hardware investment compared to the previous generation.
  • Operational Agility: Operators can deploy new tariff plans in hours instead of days. New features can be introduced three times faster, and overall deployments are accelerated by about 30%.
  • Geographic Resilience: The system is deployed across two active data centers situated about 2,000 km apart, featuring automatic recovery capabilities that trigger in under two minutes.

In-House Development and Digital Sovereignty

A defining characteristic of the vOCS 4.0 project is its end-to-end in-house development. Viettel High Tech engineered every core layer of the system, including:

  • A telecom-grade cloud-native platform
  • NFV-MANO orchestration
  • Real-time charging engines
  • Subscriber and balance management systems

This self-reliance addresses a critical strategic objective for national operators: digital sovereignty. By developing and owning the core charging infrastructure, operators reduce their dependence on foreign vendors, securing their business flexibility and operational security.

Luu Manh Ha, CEO of Viettel Networks—the entity operating the system on Viettel's network in Vietnam—emphasized the operational importance of this self-reliance: "Passing rigorous tests of real-time self-diagnosis and self-recovery is what allows an operator to keep its promise of 24/7 service to customers. Above all, owning the charging system means an operator is not dependent on foreign vendors – it safeguards digital sovereignty and preserves business flexibility."

Strategic Implications for the Global Telecom Market

The transition to vOCS 4.0 represents the next phase in Viettel's long-term technology strategy. In 2017, the predecessor system, vOCS 3.0, successfully replaced a foreign vendor's platform to serve 90 million Viettel subscribers. Across both generations, the vOCS platform now serves more than 220 million subscribers across 11 countries.

With the successful deployment of vOCS 4.0, Viettel High Tech is positioning the platform for global commercialization, targeting international operators looking to transition to 5G and expand their digital services portfolios.

Nguyen Minh Quang, CEO of Viettel High Tech, highlighted the commercial role of the platform: "The charging system is where an operator's business strategy turns into revenue in real time. We believe vOCS 4.0 is ready to help operators worldwide capture the value of 5G and digital services."

As telecommunications networks globally transition to cloud-native architectures to support 5G standalone networks, the demand for highly scalable, resilient, and cost-effective charging engines is expected to grow. Viettel's successful migration of 100 million subscribers demonstrates that in-house, cloud-native solutions can compete directly with established global vendors.