Mobile Communications Service Initiatives

When a disaster occurs, mobile phones offer a critical lifeline by enabling people to confirm the safety of their family and friends and to gather information. SoftBank Corp. strives to build disaster-resilient communications networks and ensure the swift restoration of services after a disaster.

Strengthening equipment against disasters

Provisions for power outages

Network centers have redundancy and are reinforced against earthquakes and power outages

SoftBank checks and reinforces earthquake resistance at all its base stations and has improved communications reliability by preparing backup routings for primary transmission channels. The company is implementing measures at critical base stations that increase operational time during a power outage from 48 to 72 hours.

Base stations that remain operational more than 24 hours after a power outage

SoftBank is working to reinforce provisions for generators and batteries at base stations to provide uninterrupted service even during a power outage, especially at base stations located around key areas containing facilities that play critical roles in a disaster, such as government agencies and hospitals.

Deploying mobile power supply vehicles across Japan

We have deployed mobile power supply vehicles across Japan to provide power to base stations in the case of power interruption in a disaster.

(As of March 2016)
Number of vehicles by region
Hokkaido Tohoku Kanto Shinetsu Hokuriku Tokai
4 7 11 3 3 7
Kinki Chugoku Shikoku Kyushu Okinawa Total
10 4 5 9 4 67 vehicles

Securing communications

Securing critical communications

In a major disaster, mobile phone and Internet access concentrates in the affected areas and difficulties with regular communications may result. This congestion occurs when many customers are simultaneously trying to confirm the safety of family and friends.

To prevent a large-scale network system failure caused by increased congestion, and protect emergency calls (the telephone numbers 110 and 119 in Japan) and other important communications, SoftBank may temporarily regulate communications services in accordance with the Telecommunications Business Law and in proportion to the scale of the congestion. Through this communications restriction, we are able to protect and preserve a degree of communications services while avoiding a major communications failure. We ask for our customers' understanding with regard to any inconveniences this may cause.

Restoring service

Development and implementation of a moored-balloon wireless relay system

To quickly restore lifeline mobile phone service following a disaster we have developed a moored-balloon wireless relay system for use in the event a base station is rendered inoperable. These have been positioned at key locations across Japan to provide back-up communications channels in a disaster.

The moored-balloon wireless relay system is capable of bringing wireless relay equipment to an altitude of 100 meters, covering a five-kilometer radius in open terrain. SoftBank 3G (mobile phone) (2.1GHz band) voice communications and packet transmissions (email, Internet, etc.) can be used within the coverage area. We are also conducting trial tests of a new moored-balloon wireless relay system for SoftBank 4G LTE that is deployable from ships, as part of our efforts to continuously improve this system.

Deployment of mobile base-station vehicles and portable base stations

SoftBank will deploy mobile base stations to rapidly restore service in disaster areas where base stations have been damaged or have lost power. There are many types of mobile base stations positioned across Japan for use in an emergency.

Mobile base station vehicles

Used to establish a temporary base station via satellite link-up when communication lines are damaged in a disaster. Small mobile base station vehicles use their mobility to quickly reach disaster areas.

Coverage radius Approx. 1.8km
Maximum number of phone lines 13

Used to establish a temporary base station via satellite link-up and usable land-lines when communication lines are damaged in a disaster.

Coverage radius Approx. 1.8-5km
Maximum number of phone lines Approx. 13-200 (differs depending on transmission route)

Used to establish a temporary base station via satellite link-up and usable land-lines when communication lines are damaged in a disaster. Large mobile base station vehicles are the highest capacity type, and all support SoftBank 4G LTE.

Coverage radius Approx. 5km
Maximum number of phone lines Approx. 13-700 (differs depending on transmission route)
(As of March 2016)
Number of mobile base station vehicles by region
Small Medium Large
Hokkaido 1 4 2
Tohoku 1 4 3
Kanto 3 13 11
Shinetsu 0 2 0
Hokuriku 1 2 2
Tokai 1 4 6
Kinki 1 6 4
Chugoku 1 4 2
Shikoku 0 3 2
Kyushu 1 7 3
Okinawa 0 5 1
Total 10 vehicles 54 vehicles 36 vehicles
Portable mobile base stations

Two hundred ten satellite link-up-capable portable mobile base stations are positioned across Japan. One hundred of these have vehicle-mounting capability.

Coverage radius Approx. 1.8km
Maximum number of phone lines Approx. 13
  • *
    In areas with weak reception such as tunnels, buildings, underground and mountainous areas service may not be available even within the coverage radius. Please note that there may also be interruptions to service even in cases where the signal strength indicators on mobile devices display maximum level.
  • *
    The maximum number of phone lines is dependent on the number of landlines that can be prepared in a disaster.

Rapid restoration of service at damaged base stations

Creating new transmission routes at existing base stations

When damaged transmission lines render base stations inoperative, these base stations will be brought back into operation by establishing interexchange transmission routes using microwave relays, temporary dedicated lines, and equipment for satellite communications.

Microwave relays

Where there are no impediments to transmissions between base stations we will set up parabolic antennae that use microwave signals in place of damaged fiber optic lines.

(As of March 2016)
Number of relays by region
Number by frequency band
5GHz 11GHz 18GHz
Hokkaido 2 6 6
Tohoku 2 6 6
Kanto 4 6 6
Hokuriku 2 6 6
Tokai 2 6 6
Kinki 2 6 6
Chugoku 2 6 6
Shikoku 2 6 6
Kyushu 2 6 6
Total 20 54 54
Reconstruction of base stations

Should a base station become inoperable due to damage to the facility or communications equipment, it will be rebuilt in the same place after confirming the safety of the ground and foundations and that customers are present to use the base station.

Providing means of communication

Loan of mobile phones to local governments, etc.

SoftBank has positioned 1,500 satellite and mobile phones at locations across Japan for use in relief and recovery activities in disaster areas, and has prepared a structure whereby they can be loaned free of charge to local governments, public organizations, NPOs and other organizations.

Securing means of communication for disaster victims

SoftBank has designated 4,200 mobile phones and PHE Home Phones (PHS) for evacuees to use free of charge at evacuation shelters and areas where temporary base stations are established in a disaster.

  • *
    As of March 2016