Viettel moves 100 million subscribers to homegrown cloud-native charging stack

Viettel has migrated more than 100 million subscribers and 5,000 tariff plans to vOCS 4.0, its latest in-house cloud-native online charging system, the operator's technology arm Viettel High Tech announced. The cutover took three months on Viettel's live national network with no service disruption.

The migration is the second time Viettel has replaced a foreign charging platform with its own code. The previous version, vOCS 3.0, went live in 2017 and replaced a foreign vendor's system serving 90 million Viettel subscribers. The subscriber base has grown by roughly 10 million, or about 11%, in the interim.

How did Viettel de-risk the cutover?

Viettel High Tech said it used real-time data synchronization, parallel running and a phased cutover, with instant rollback available at every stage. Those controls matter for practitioners: charging migrations on live networks are among the highest-risk BSS projects, because a failed cutover bills customers incorrectly or drops sessions outright.

The company said it developed every core layer of vOCS 4.0 in-house. The stack spans a telecom-grade cloud-native platform, NFV-MANO orchestration, real-time charging, and subscriber and balance management.

"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," Viettel Networks CEO Luu Manh Ha said in a statement on Tuesday. "Above all, owning the charging system means an operator is not dependent on foreign vendors – it safeguards digital sovereignty and preserves business flexibility."

What does the new platform actually deliver?

Viettel High Tech claims vOCS 4.0 handles over 300,000 transactions per second at latency below 5 milliseconds. The platform converges 2G through 5G and fixed services onto a single charging instance. For context, 300,000 transactions per second is enough headroom to charge a base the size of Viettel's — one of Asia's largest single-country subscriber bases — while absorbing event spikes from prepaid data usage.

The vendor also claims faster commercial cycles:

• New tariff plans can be deployed in hours instead of days.
• Hardware investment falls by up to 50% because the charging system shares infrastructure with the network.
• Two active data centres back the platform, with automatic recovery in under two minutes.

These figures come from Viettel High Tech's own announcement and have not been independently verified. Vendor throughput and cost-reduction claims should be read as marketing until a third-party operator reports field results. The resilience figure, however, is testable: two active data centres with sub-two-minute recovery align with the self-healing capabilities Luu described.

Why does this matter beyond Vietnam?

Viettel High Tech said it is now offering vOCS 4.0 to operators worldwide. The pitch targets mid-size carriers that want to escape foreign OCS licensing costs and long integration cycles, a cohort that has grown as telecom operators push digital sovereignty agendas in developing markets.

"We believe vOCS 4.0 is ready to help operators worldwide capture the value of 5G and digital services," Viettel High Tech CEO Nguyen Minh Quang said.

Viettel itself is the proof case, and a strong one: a full national migration of 100 million subscribers across three months with zero reported downtime is a reference few incumbent BSS vendors can match on that scale. The company has now run its own charging stack for eight years, since the 2017 replacement, which answers the durability question buyers usually raise about newcomer platforms.

The commercial test comes next. Viettel High Tech gave no named international customers, pricing, or deployment timelines in the announcement, so the platform's export prospects will become clear only when the first carrier outside Vietnam signs and discloses results.