Vietnamese Engineers Build Telecom Billing System for 100 Million Subscribers

In an announcement on October 26, Viettel High Tech (VHT) stated that the system received recognition in the “Excellence in Technology Deployment – Asian Operator” category at the Telecom Review Excellence Awards 2026. This milestone marks the first time a Vietnamese enterprise has earned recognition at the awards.

An Online Charging System (OCS) serves as a mission-critical component for telecom operators. It evaluates and bills every call, message, data session, service package, and promotional offer in real time. The sector presents high technological barriers, historically dominated by a handful of global tech conglomerates.

Viettel began internal development of its charging system in 2012 after using foreign vendor solutions. By 2017, the operator deployed vOCS 3.0, replacing imported systems across 90 million domestic subscribers in Vietnam before expanding to overseas markets across Asia, Africa, and the Americas.

VHT initiated the development of vOCS 4.0 in late 2020 using a Cloud-Native architecture. Two years later, the platform supported its first one million subscribers. By 2026, the architecture was fully prepared to scale to over 100 million subscribers.

A major breakthrough of vOCS 4.0 lies in its throughput capacity: processing more than 300,000 transactions per second—exceeding one billion transactions per hour—with latency under 5 milliseconds. Compared to its predecessor, the platform cuts hardware capital expenditure by 50%, shortens deployment timelines by roughly 30%, and triples the speed of introducing new features.

The architecture deploys concurrently across two data centers separated by approximately 2,000 kilometers. If one site encounters an outage, the other automatically takes over, restoring full service in under two minutes.

Viettel High Tech engineers and partner units during the mobile subscriber migration to the vOCS 4.0 system

To achieve this level of performance, VHT representatives affirmed that they mastered and engineered the core technology stacks in-house. These include a Cloud-Native platform aligned with international telecommunications standards, Network Functions Virtualization Management and Orchestration (NFV-MANO), and specialized engines for real-time transaction processing, subscriber data management, and balance tracking.

According to Mr. Nguyen Minh Quang, General Director of Viettel High Tech, the platform simultaneously serves 2G through 5G networks and fixed-line services on a single converged infrastructure. Business units can configure service bundles via standardized templates coupled with automated testing. This capability reduces the time required to launch a new data package from several days to just a few hours.

“vOCS 4.0 is primed to meet the demands of domestic and international operators seeking to unlock the commercial value of 5G and digital services,” Mr. Quang said, emphasizing that the OCS acts as the operational engine where commercial policies translate into real-time revenue.

Over the past three months, VHT collaborated with ecosystem partners including Viettel Network and Viettel Telecom to migrate all domestic mobile subscribers and approximately 5,000 active service packages onto vOCS 4.0. The migration took place on the live network without service interruption. VHT is currently rolling out the platform across Viettel’s 10 international markets while preparing commercial delivery to external global operators.