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Improving Network Reliability

We endeavor to build disaster-resistant communications networks, facilities, and equipment.

Disaster-resistant communications networks

Curbing the impact of damage to transmission lines

Trunk line multi-routing

The key to constructing networks that keep people connected is to design for continuity of communication services by making connections robust enough to withstand disruption and ensure that they can be quickly restored even if disrupted. Trunk line multi-routing is one way of achieving this aim. Our nationwide network of trunk lines has been designed to secure communication and prevent disruption of services over the network as a whole by automatically diverting transmission through other routes when a certain route is damaged.

Trunk line multi-routing

Curbing the impact of cable breakages

Submarine cables designed to withstand disasters

We have laid a high reliability, low latency submarine cable (ASE*) that not only links Japan with Hong Kong and Singapore by the shortest possible route, but also avoids the Bashi Channel off the southern coast of Taiwan, a zone that is susceptible to earthquakes, typhoons, and other natural disasters.

*ASE:Asia Submarine Express

Submarine cables designed to withstand disasters

Curbing the impact of damage to communications buildings

Distributed location of important communications buildings

If communication buildings (important communication buildings) fitted with transit switches suffer disaster damage, all communications via such buildings may be severed. Distributing important communications buildings in different locations helps avoid the risk of multiple buildings suffering disaster damage at the same time.

Nationwide round-the-clock monitoring

Disaster-resistant communications facilities and equipment

Withstanding strong typhoons and preventing inundation by tsunamis or floods

NTT's communications buildings and steel towers are designed to withstand strong typhoons with gusts of 60 m/s. Our facilities are also equipped with flood barriers or flood doors according to location to prevent inundation by tsunamis or floods, and cable connections are also waterproofed.

Wind and water damage


Designed to withstand Shindo 7 earthquakes

NTT's communications buildings and steel towers are designed to withstand earthquakes of a seismic intensity of 7 on Japan's Shindo scale. The switching, electrical, and other communications equipment housed in our communications buildings is also firmly secured to prevent its collapse.


Backup power to guard against grid power outages

Our communications buildings and wireless base stations are equipped with backup power sources(batteries, generators) to keep them running for extended periods in the event of sudden power outages. We also have power supply vehicles stationed around the country to substitute for backup power sources that look likely to cease functioning.

Power outages

Fire prevention and fire proofing

We equip our communications equipment rooms with fire doors or shutters, and connections between communications buildings and cable tunnels with firewalls and fire doors. We guard against the outbreak of fires within our communications buildings by equipping them with smoke detectors and fire extinguishing equipment. We also use flameproof communications cables.