What Is a Withheld Number Call?
It is a call that shows up on your screen as "No Caller ID", "Withheld", "Private Number" or "Unknown". The caller has set things up so that their own phone number is not passed on to you. In Japan, dialling 184 in front of a phone number stops your number from being shown to the person you are calling. This works off the Number Display mechanism, and it means the caller is deliberately hiding their number.
Some people who withhold their number have perfectly good reasons for it - hospitals and school teachers, for instance - but the reality is that withheld numbers are also widely abused for nuisance calls and scam calls. Surveys by the Ministry of Internal Affairs and Communications show that enquiries about withheld calls rise year after year, and they are a particular source of anxiety for anyone who has only just started carrying a smartphone.
Who Is Actually on the Other End?
Withheld calls fall into a handful of patterns. Knowing the character of each one lets you judge calmly when the phone rings.
Nuisance and Sales Calls
This is the most common pattern by far. Once you know their number they get blocked, so they call with the number withheld. Property sales, fibre broadband pitches and investment offers are the classic examples. Telemarketing firms know that showing their number lands them on your block list, so they use withheld numbers to work around blocking. Set your phone to reject withheld numbers, however, and the trick stops working. Our guide to fending off nuisance calls is worth a look as well.
Scam Calls
The people behind impostor scams and bogus billing scams sometimes withhold their number to hide who they are. Whatever they claim - "this is the police", "this is your bank" - the fact that the call arrives with the number withheld is itself suspicious. The police and banks do not normally call individuals from a withheld number. Phone scam tactics grow more sophisticated every year, but "withheld number plus a claim to be a public authority" is a textbook scam pattern. It is reassuring to read up on how to report phone scams too.
Silent and Prank Calls
Silent calls - where the caller says nothing and hangs up - and calls made purely as a prank also arrive with the number withheld. If silent calls keep coming, treat them with care: they may be someone checking whether you are at home, or stalking behaviour. One call on its own is not worth worrying about, but if they come repeatedly at the same time of day, start keeping a record.
Legitimate Calls
There are also cases where the number is withheld for a legitimate reason: a hospital ringing with test results, a teacher from school, or a recruiter from a company. That said, callers like these usually tell you in advance that they will be calling from a withheld number. If you are job hunting, bear in mind that a company's main switchboard number is sometimes set to withhold, so if you are expecting such a call it is reasonable to answer.
Should You Answer a Withheld Call?
To give you the conclusion first: as a rule, you do not need to answer.
If the matter is genuinely important, the caller will either ring back with their number shown or leave a message on your voicemail. A caller who rings repeatedly from a withheld number and never leaves a voicemail is not one you need to pick up for. A call with no voicemail message left behind is almost certainly a nuisance or sales call.
If you do have reason to expect a withheld call, though - you are waiting on hospital test results, or you are job hunting and expecting to hear from an employer - then answering is fine. Even then, stick to the basic rule: if you are asked for personal information, do not give it.
Some people worry that not answering means missing something important. But if the message really matters, the other side will always reach you by some other route: voicemail, SMS or email. There is virtually no such thing as an important message that is abandoned after a single withheld call.
How to Reject Withheld Numbers on iPhone
iPhone has a feature called Silence Unknown Callers.
- Open the Settings app
- Tap Phone
- Switch on Silence Unknown Callers
With this turned on, calls from numbers that are not in your contacts, and calls with the number withheld, are silenced automatically and sent to voicemail. They still appear in your call history, so you can check them afterwards.
One caveat: the feature silences not only withheld numbers but every number that is not saved in your contacts. A delivery driver, or a business contact calling you for the first time, gets silenced too - so when you are waiting for an important call, consider switching it off temporarily.
How to Reject Withheld Numbers on Android
The exact steps on Android vary by handset and manufacturer, but the general procedure is as follows.
- Open the Phone app
- Tap the menu (three dots) at the top right
- Choose Settings, then Blocked numbers
- Switch on Block unknown callers
Depending on the handset, the wording may differ - "nuisance call block", "call rejection settings" and so on. On Samsung devices there is a Block numbers item inside the Phone app's settings, where you can switch on the toggle for blocking withheld numbers. On Google Pixel you can set it from the Phone app under Settings, then Blocked numbers.
Carrier Services for Rejecting Withheld Numbers
Quite apart from your handset settings, the mobile carriers offer their own services for rejecting withheld numbers.
- Docomo: Bangou Tsuuchi Onegai Service, or Please Show Your Number Service (free) - plays a message asking the withheld caller to show their number. Set it up by dialling 148
- au: Bangou Tsuuchi Request Service, or Number Notification Request Service (free) - plays a similar message. Set it up by dialling 1481
- SoftBank: Number Block (110 yen a month) - blocks nuisance calls including withheld numbers. Set it up by dialling 144
Carrier services block at the level of the phone line itself, which makes them more dependable than a handset setting. Silence Unknown Callers on your phone merely stops the ringtone, whereas with a carrier service the call never reaches your handset at all - which also keeps battery drain down. The Docomo and au services are free, so there is nothing to lose by switching them on.
If You End Up Answering a Withheld Call
Answering a withheld call is nothing to panic about. Just keep the following in mind.
- If you are asked for personal information such as your name or address, do not answer
- Do not simply say "yes" - ask who is calling and confirm who you are speaking to
- The moment anything feels off, hang up. It is not rude
- If it is a silent call, hang up straight away
- If you are asked to "help us with a survey", decline. It may be a technique for extracting personal information
The first word out of your mouth deserves particular care. Cases have been reported overseas where answering with nothing but "yes" led to that recording being captured and misused. It is not yet common in Japan, but getting into the habit of asking who is calling gives you peace of mind.
When Withheld Calls Keep Coming
If withheld calls arrive several times in one day, you may be looking at harassment or stalking rather than mere sales calls. Work through the following steps.
- Record the date, time and number of calls (screenshots are fine)
- Set up your carrier's service for rejecting withheld numbers
- If the calls continue regardless, contact the police consultation line on #9110
- Under the Anti-Stalking Act, repeatedly calling and then saying nothing counts as "stalking and related conduct"
Taking your call records with you when you consult the police makes the process go more smoothly. In serious cases it is also possible to seek disclosure of the caller's details through the telecommunications carrier.
In Summary
As a rule, withheld calls are fine to leave unanswered. If the matter is important, the caller will ring back with their number shown or leave a voicemail. If it worries you, set up Silence Unknown Callers on iPhone or your carrier's service for rejecting withheld numbers. And when withheld calls keep coming, keep a record and consult the police if you need to. Installing a nuisance call filter app is effective too, as a measure against nuisance calls that are not withheld. It is worth going over our advice on protecting your phone number privacy as well.