Completion of Full Virtualization of Mobile Core Network

NTT Docomo, Inc. (hereinafter, Docomo) has completed the full virtualization of its mobile core network (hereinafter, core network), which serves as the foundation for mobile voice and mobile data communication services used by over 90 million customers. This was achieved through network equipment transitions carried out by the end of March 2026 and the termination of 3rd generation mobile communication (3G) services ※1.

As a result, Docomo's core network has transitioned from a configuration dependent on conventional dedicated hardware to one where functions are implemented as software on general-purpose servers, evolving into a more flexible, stable, and cost-efficient communication infrastructure.

　　　　　　　　　　　　　　　　　　　＜Overview Diagram＞

■ Background

Conventional core networks were built using dedicated hardware for each function, posing challenges such as the time required for equipment expansion and configuration changes, and the need for prompt on-site maintenance in the event of device failure.

To address these challenges, Docomo began basic research on network virtualization in 2005, promoted international standardization through standardization bodies such as ETSI※2 and 3GPP※3 from 2014, and successfully conducted a proof-of-concept in 2014※4. Subsequently, in March 2016, Docomo pioneered the world's first commercial operation of multiple vendors' EPC※5 software running on an integrated virtualization platform※6. Docomo has progressively advanced network construction independent of specific hardware, in step with technological advancements and standardization trends across the telecommunications industry.

Since then, Docomo has continuously pursued migration in line with the timing of existing equipment upgrades, and has now achieved full virtualization of the entire core network.

■ Overview of Full Virtualization

Virtualization refers to implementing various functions that constitute the core network as software on general-purpose servers, rather than dedicated devices, by introducing a virtualization layer (hypervisor or container virtualization). Full virtualization is a mechanism that enables flexible control and operation of the entire network by virtualizing all devices that constitute the network. This makes it possible to change equipment configurations and optimize function placement through software control.

■ Effects

By fully virtualizing Docomo's core network, it evolves into a highly flexible configuration less constrained by physical limitations.

• Improved Communication Reliability

Even if an equipment failure occurs, the system automatically detects abnormalities in the software or hardware constituting the network, and immediately executes auto-healing※7 across the entire core network, restarting and reconfiguring functions on another healthy virtual resource. This shortens the period of single-system operation and contributes to the provision of stable communication services.

• Faster Equipment Capacity Expansion

General-purpose hardware can be shared by multiple systems, allowing dynamic utilization of available resources from an integrated platform's resource pool. This shortens the time required to secure necessary equipment capacity when new services are launched or traffic increases. Furthermore, an auto-scaling function becomes possible, which automatically expands network equipment capacity in response to natural disasters, improving connectivity.

• Improved Operational Efficiency and Environmental Impact

By consolidating general-purpose servers and utilizing the latest hardware, it is possible to reduce equipment installation space and power consumption, contributing to both improved operational efficiency and reduced environmental impact.

■ Collaboration with Partners

The realization of this full virtualization has been advanced through the promotion of international standardization activities in ETSI NFV and 3GPP, and the expansion of virtualization technology application scope, in cooperation with partners including Cisco Systems G.K., Dell Technologies Inc., NEC Corporation, and Ericsson Japan K.K.

■ Future Developments

Docomo will continue to utilize the latest cloud technologies for automation of equipment construction, labor-saving operations, and reduction of equipment costs. Furthermore, Docomo will promote the construction of a hybrid core network※8 that utilizes public clouds in addition to on-premises environments.

Through these efforts, Docomo will further advance and optimize its network, which is the foundation of mobile communication services, and continue to provide a communication environment that customers can use with greater peace of mind and convenience.

※1 In this text, "full virtualization" refers to the migration of mobile core functions such as 5GC, EPC, and IMS to operate as software on general-purpose servers. It does not include network devices such as routers and switches, or some functions that are not planned for virtualization according to our standards.

※2 ETSI (European Telecommunications Standards Institute) is an international standardization body for telecommunications based in Europe. Telecommunication carriers and equipment vendors from within and outside Europe participate in promoting standardization of telecommunication network-related technologies, including Network Function Virtualization (NFV).

※3 3GPP (Third Generation Partnership Project) is a standardization project that formulates international standard specifications for mobile communication systems, including mobile phones. From 3rd generation (3G) to 4th generation (4G/LTE) and 5th generation (5G), standardization bodies, telecommunication carriers, and equipment vendors from various countries and regions participate in formulating specifications for radio access methods, core networks, and service specifications. Japanese standardization bodies and telecommunication carriers also participate in 3GPP activities.

※4 "Successful Proof-of-Concept for Commercialization of 'Network Virtualization Technology' with Six Major Global Vendors" (Press Release, October 14, 2014)

※5 EPC (Evolved Packet Core) is communication equipment that accommodates various radio accesses such as LTE, provides customer authentication, mobility control to continue data communication while moving, billing functions, and connects to external networks such as the Internet.

※6 "World's First Development of Network Virtualization Technology Capable of Operating Multiple Vendors' EPC Software" (Press Release, February 19, 2016)

※7 Auto-healing is a technology that automatically detects abnormalities in network software or hardware failures, and immediately restarts and reconfigures functions on another healthy virtual resource without human intervention.

※8 "First in Japan to Launch Commercial 5G Core Service Built on AWS, and World's First Success in Automated Core Network Construction Using AI" (Press Release, March 2, 2026)

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　　　　　　　　　　　　Comments from Partner Companies

Mr. Hitoshi Kida, Executive Officer, Head of Service Provider Business, Cisco Systems G.K.

I sincerely congratulate NTT Docomo on achieving full virtualization of its mobile core network. We are extremely honored to have contributed to building a network infrastructure that can automate the complex network configuration settings for a large number of network devices and demonstrate high scalability and performance in NTT Docomo's large-scale and mission-critical environment.

As a long-standing partner, we will continue to walk alongside Docomo in its future endeavors and provide our full support.

Mr. Andrew Vaz, Vice President, Dell Technologies Inc.

NTT Docomo's completion of core network full virtualization is a landmark achievement for the industry. Dell PowerEdge servers underpin this accomplishment, supporting NTT Docomo's virtualized infrastructure. This collaboration reflects our shared goal of building more flexible, efficient, and resilient networks.

Mr. Yutaka Nishigori, General Manager, Core Network Division, NEC Corporation

NTT Docomo's completion of mobile core network full virtualization is an extremely significant initiative that demonstrates the advancement and future development of Japan's mobile communication infrastructure.

NEC has supported the realization of virtualized networks end-to-end, not only through the virtualization of mobile core networks including IMS, EPC, and 5GC, but also by introducing mechanisms to automatically control and manage a series of operations such as their construction, deployment, expansion, and recovery from failures.

Through many years of collaboration between our two companies, we believe that a virtualized network infrastructure combining reliability and flexibility has been built, leading to the completion of full virtualization. We understand that the establishment of such a foundation creates an environment conducive to future initiatives for advanced operations utilizing AI and network evolution.

NEC will continue to work with NTT Docomo to advance and enhance the entire mobile communication infrastructure.