Phones Do Not Get Through During a Disaster
When a major earthquake or typhoon strikes, huge numbers of people call at once, the telephone network is overwhelmed and calls stop connecting. In the aftermath of a major disaster such as the 2011 Great East Japan Earthquake, calls into the affected area concentrate far above normal levels, and carriers may restrict some outgoing calls.
At times like this it is vital to know how to check that your family is safe. "The phone will not connect" does not mean "I cannot reach them". Using the disaster message dial (171) you can leave a message confirming you are safe even when the network is congested. Understanding how phone numbers work also helps you choose the right means of communication in a disaster.
Call restrictions during a disaster exist in order to keep the lines for emergency calls (110 and 119) open. By limiting ordinary calls, the network ensures that life-threatening emergencies get through. That is exactly why safety checks should use 171, social media or other channels rather than voice calls.
What Is the 171 Disaster Message Dial?
The 171 disaster message dial provided by NTT is a service that lets you record and play back voice messages during a disaster. Even when calls will not connect, you can leave a message to let people know you are safe.
- Cost: there is no charge for the message centre itself, and calls from an NTT East or NTT West phone service are free as well. For calls from a mobile phone or another carrier's line, check the call charges with your own provider
- Recording length: up to 30 seconds per message
- Capacity: up to 20 messages per phone number, and fewer in some activations depending on how NTT configures the service
- Retention: until that activation of the 171 service ends (set by NTT for each disaster and announced when the service starts)
Because 171 runs over the telephone network, it works even when the internet is unavailable. You can use it from a landline, a mobile phone or a payphone.
How to Record a Message
- Dial 171
- Press 1 (record)
- Enter your own phone number, such as your home landline number
- Follow the voice guidance and record a message of up to 30 seconds
Example: "This is [name]. I am safe. I have evacuated to [name] Elementary School."
Keep the message short and stick to the essentials. Three points are enough: who you are, whether you are safe, and where you are. Thirty seconds is shorter than you expect, so it goes more smoothly if you have thought about what to say in advance.
How to Play Back a Message
- Dial 171
- Press 2 (playback)
- Enter the phone number of the person whose safety you want to check
- The recorded message plays
If no message has been recorded, guidance saying there are no messages plays instead. Wait a while and check again.
Decide This With Your Family in Advance
To use 171 your family needs to have agreed on which phone number messages will be left under. Without that agreement, family members leave messages under different numbers and nobody can find anybody else's.
- Using your home landline number as the reference is the usual choice, because everyone in the family knows it. If you have changed your number, be aware of how number recycling works as well
- If you have no landline, agree on one family member's mobile number instead, for example the father's number
- Make sure everyone in the family remembers that number. Saving it in a notes app on your phone also helps
- Agreeing on a meeting place at the same time gives you even more peace of mind
web171 (the Web Version)
There is also web171, which lets you leave written messages from a smartphone or computer.
- URL: https://www.web171.jp/
- Messages are text, so it works even in situations where you cannot make a call
- Usable anywhere you have an internet connection
- It is linked with the voice-based 171, so messages can be checked from either side
If you have internet access, web171 is the easier option. Because it is text, there is no worry about not being able to make out what was said.
Each Carrier's Disaster Message Board
Besides 171, the major mobile carriers run their own disaster message board services.
- Docomo: disaster message board
- au: disaster message board
- SoftBank: disaster message board
- Rakuten Mobile: disaster message board
These are reached from each company's official website or app. Names and availability change over time, so check the carrier's own announcements too. Using them alongside 171 gives you more ways to confirm that people are safe.
How to Use the Phone During a Disaster
- Emergency calls (110 and 119) come first: if life is at risk, call without hesitation
- Use 171 or social media for safety checks: avoid ordinary calls, which put pressure on the network
- Prefer email or LINE over calling: text messages use far less bandwidth than a voice call, so they get through more easily when the network is congested
- Keep it brief: if a call does connect, say what you need to say and hang up
- Make use of payphones: payphones are given priority during a disaster, and emergency calls can be made without inserting coins
The most important thing during a disaster is to share the network. Every long call by one person makes it that much harder for someone else's emergency call to connect. Do your safety checks with 171 or social media, and use the voice network only when you truly need it.
171 Trial Days
Outside of actual disasters, 171 is open for trial use on the following days. Use them to practise.
- The 1st and 15th of every month
- 1 to 3 January (the first three days of the new year)
- Disaster Preparedness Week (30 August to 5 September)
- Disaster Preparedness and Volunteer Week (15 to 21 January)
Note that trial use may be unavailable while a disaster is in progress.
Practising once as a family means you can use it without panicking when it matters. Children and older relatives in particular are often unfamiliar with the steps, so practising together on a trial day is well worth it. If a family member's contact details have changed, check our checklist for changing your phone number too.
Emergency Alert Messages on Your Phone
During a disaster your phone may receive emergency alert messages, known in Japan as area mail. Earthquake early warnings, tsunami warnings and evacuation instructions are delivered automatically. Make sure this feature is enabled in your phone settings; the option sits with the other notification settings, though the exact label varies by model.
Emergency alerts are delivered over the mobile carrier network, so they arrive automatically as long as a SIM card is installed. Note, however, that whether alerts arrive depends on your handset and the terms of your contract, including with a budget SIM, so check before you sign up.
Summary
In a disaster: call 171, press 1 to record, enter your home number, and leave a message. Remember just that and you can tell your family you are safe. Decide now, while things are calm, which number your family will leave messages under. Trial use is available on the 1st and 15th of each month, so do try it out at least once.