The real-time charging system (OCS) for a telecommunications operator is similar to Core Banking for a bank, but it is many times larger and more complex, considered the "heart" of the network because it contains all data about customers, products, services, and business policies.

Imagine a poor mother living in a border village in Dien Bien. Her son got married, had children, and lives in Hanoi, only able to visit his mother once a year. Her joy is calling and talking to her grandchildren, but her economic conditions do not allow her to do this daily. How can she hear her children's voices and talk to her grandchildren for only 10,000 VND per month, while urban dwellers still use packages costing 100,000 VND, 1 million VND? The network cannot offer a 10,000 VND package to everyone, but if a 100,000 VND package is applied to everyone, the mother in Dien Bien will not be able to use mobile services.

Viettel's OCS system, vOCS 3.0 and recently 4.0, was designed to solve this problem, providing every Vietnamese with a unique package based on their consumption needs and payment ability.

By mastering the charging system, Viettel can design the most suitable packages and services for Vietnamese users nationwide.

The story of "Vietnamese can do it!"

By the time the first vOCS version was born in 2011, Viettel had spent over 7 years renting charging systems from the world's leading partners. Many limitations in service provision when using rented systems led Viettel people to think of a solution that no telecommunications operator in the world had yet implemented: self-developing.

"At that time, Mr. Trung [Mr. Tong Viet Trung, former Deputy General Director of Viettel Group] told us: We have to do it ourselves. Depending on partners like this is like having our hands and feet tied" Mr. Nguyen Van Vinh, the oldest member of the early vOCS development team recalled.

OCS is a system that monitors usage and charges fees. Therefore, the range of packages and services a telecommunications operator can provide to users depends on whether the OCS provider supports that service. For example, with vOCS, users can buy a momentary package of 2 hours to watch movies or go online when needed, which was not possible with older systems.

Viettel's first vOCS development team was much smaller in scale than the world's OCS providers, but succeeded in creating a product with unprecedented scale and features.

With only 20 members, Viettel's people started developing their own OCS. This becomes even more impressive when, globally, only the three largest OCS providers supply all network operators and have engineering teams several dozen times larger. While the partner stated, "it takes 2,000 engineers and continuous development over 4 years," Viettel's people were ready to take on the challenge with 20 people.

Determined to develop the OCS system following the philosophy "small team, big task," team members simultaneously handled many different duties, working regardless of day or night. They tirelessly experimented and reworked upon failure. This process lasted so long that the implementers couldn't remember how many times they had failed.

Technology moving forward, no one is left behind

By April 2017, vOCS 3.0 was successfully deployed with 90 million subscribers. To date, this "heart of the network" system has been deployed by Viettel in 9 countries, managing 150 million subscribers, making it one of the largest and most feature-rich OCS systems globally.

The new system has saved Viettel over 70 million USD in investment costs. However, money is not the most important benefit.

The ability to personalize created a turning point for user benefits, allowing the construction of packages that meet the need to hear children's and grandchildren's voices for poor parents in remote areas for 10,000 VND/month or help everyone find packages suitable for their economic conditions and needs. Personalization places customers at the center of Viettel's service. And that personalization also made Viettel's initial dream a reality.

With these achievements, Viettel's vOCS won the Gold Award in International Business in London. Viettel became one of the top 3 largest OCS producers globally. More notably, Viettel is the only telecommunications operator in the world to master its own vOCS technology, bringing the Vietnamese group closer to the world's largest telecommunications equipment providers like Ericsson, Huawei. Viettel's technology has also been patented in the US, protected for 18 years, and exported to many markets where Viettel operates.

vOCS is continuously improved to remain the "heart" in the journey of popularizing digital services to everyone. In 2023, the fourth version of vOCS (vOCS 4.0), supporting the upcoming wide deployment of 5G mobile generation and new generation digital services, was tested on Viettel's network with 2 million subscribers.

"Viettel continues to adhere to the beautiful aspiration passed down from generation to generation, always innovating for people, ensuring that as technology advances, no one is left behind" said Major General Tao Duc Thang, Chairman and General Director of Viettel, on the occasion of the group's 35th anniversary.