Calls From Unknown Numbers Are Nothing to Fear
Once you have a smartphone, calls will come in from numbers you do not know. "Who is this?" "Should I pick up?" It is unsettling, but you will be fine as long as you stay calm.
Calls from unknown numbers fall into three broad patterns.
- Wrong numbers - someone simply mistyped a digit
- Sales and solicitation calls - a company that wants to sell you something
- Scam calls - a criminal after your money or your personal information
The call may of course be perfectly legitimate, too: a hospital, your school, or a friend's new number. What matters is deciding calmly instead of panicking.
The Basic Rule: You Do Not Have to Answer
There is nothing wrong with letting a call from a number you do not know go unanswered. If the matter really is important, the caller will do one of these things.
- Leave a message on your voicemail
- Call you again
- Tell you what they want by SMS (text message)
A call that rings once, leaves nothing behind and stops may be a sales call or a wrong number - or a one-ring call placed to make you dial back. Leaving it alone is fine, but avoid calling back yourself.
Try Searching the Number
Searching the web for the number that called you will often tell you where the call came from.
- Copy the number from your call history (press and hold it)
- Search for it in your browser (for example, search for "0312345678")
- The results may show a company name, or comments left by other people
If the comments describe it as a nuisance call or a scam, do not call the number back. If a company name appears, stop and think about whether you have any dealings with that company. A reverse lookup service like this one brings those reports together in one place. Our guide on how to handle anonymous calls is worth reading as well.
What the First Digits Tell You
Just looking at the first few digits of a phone number gives you a rough idea of what kind of call it is. That gives you something to go on when the phone rings.
- 03, 06 and similar: landline numbers. Many of them are calls from companies and shops
- 090, 080, 070: mobile numbers. Most likely a call from an individual
- 050: IP phone numbers, used widely for company call centers, calling apps and much else
- 0120, 0800: toll-free numbers. A call from a company, and calling back costs you nothing
- 0570: Navi Dial. If you call back, the charge is yours to pay, and it is excluded from flat-rate call plans
If you would like to know more about the different kinds of number, take a look at how caller ID works.
What to Do if You Have Already Answered
Even if you have picked up a call from a number you do not know, there is no need to panic. Just keep the following in mind.
Do not give your name first
Rather than "Yes, this is [your name]", answer with nothing more than "Hello". The rule of thumb is to give away nothing about yourself until you know who is calling.
Say no if you are asked for personal information
If you are asked for your name, your address, the name of your school or details about your family, say that you cannot answer. Even a caller with legitimate business may ask you to confirm who you are, but you do not have to answer on the spot. Hang up, then call back yourself on the number printed on the company's official website or on your bill, and check from there. Telling a stranger nothing personal is central to protecting your phone number privacy.
Hang up straight away if something feels wrong
If you hear things like "Please transfer the money" or "You need to complete the procedure right now", end the call at once. Hanging up partway through is not rude. Your own safety comes first.
A recording gives you peace of mind
If you have answered a call that seems suspicious, recording it leaves you with evidence afterwards. Whether call recording is available depends on your handset and your OS version, so check while things are calm whether a record button appears on screen during a call. With a recording to hand, you can describe exactly what happened when you talk to a parent or to the police.
Things to Watch When You Call Back
If you do call back a number you do not know, take care over the following.
- Search the number first and work out where the call came from
- Numbers beginning 0570 (Navi Dial) charge the call to you (with NTT DOCOMO Business's Navi Dial, 11 yen including tax per 20 seconds from a mobile phone, as of August 2026). They are excluded from flat-rate call plans
- Do not call back numbers beginning with a plus sign, which are international. One known trick is to route you to an expensive overseas number so that the person calling back is billed heavily
- If you call back and nobody answers, do not keep trying
Getting into the habit of searching a number before you call back helps you steer clear of phone scams. It is safer not to call back numbers that other people have reported as nuisance calls. Anyone can post a comment, though, so even when a company name comes up, do not judge by the comments alone - call the number listed on that company's official website and check. Our article on how to fight nuisance calls is worth reading too.
Cut Down Nuisance Calls in Your Phone's Settings
To receive fewer calls from unknown numbers, go through your phone's settings.
- iPhone: turn on Settings, then Phone, then Silence Unknown Callers, and calls from numbers that are not saved in your contacts stop ringing. They still appear in your call history and go to voicemail, so you can notice them later and call back
- Android: turn on spam call filtering in the settings of the Google Phone app, and you get a warning for any number that may be a nuisance call
You can change these settings again at any time, so do give them a try. Learning how to set up call rejection as well lets you block one particular nuisance number precisely.
Learn the Common Nuisance Call Patterns
Nuisance calls follow a few typical patterns. Knowing them in advance helps you keep a level head when a call arrives.
- One-ring calls: the phone rings once and cuts off. Getting you to call back is a known aim of this trick. Not every single missed ring is a one-ring call, but it is safer not to dial back a number you have no reason to know
- Automated voice calls: a recorded message saying that you have an unpaid bill, or that your bank account is about to be frozen. An automated voice that rushes you into paying or tapping something is a classic scam pattern. Even if it sounds as though it might apply to you, do not follow the instructions there and then - hang up, look up the official contact details yourself, and check
- Calls posing as a survey: the caller asks for help with "a short survey" and draws personal information out of you. Do not give your name or your address
Talk to a Parent or an Adult You Trust
When you cannot decide what to make of a call, the best thing you can do is talk to a parent or an adult you trust. Simply saying that you have had a call like this is enough to get sensible advice.
Always tell an adult if a call involved any of the following.
- Money came up
- You were told not to tell anyone
- You were asked for personal information
- The call frightened you
There is no need to carry it alone. In Japan, #9110 is the police line for worries that are not emergencies calling for 110. If it is urgent, dial 110.
Summary
You do not have to answer a call from a number you do not know. Even if you do answer, you are safe so long as you keep to three rules: do not give your name, do not give personal information, and hang up if anything feels wrong. When in doubt, search the number or talk to an adult. Make use of your phone's nuisance call filtering settings too, and you can go on enjoying your smartphone with confidence. Learning the basics of protecting your phone number makes it more reassuring still.