What Are Anonymous Calls?
An anonymous call is a phone call where the caller intentionally hides their caller ID. In Japan, callers can withhold their number by dialing "184" before the number or by configuring their line settings. Both landlines and mobile phones can make anonymous calls, and the recipient's display will show "Anonymous" or "Withheld." This applies regardless of whether the call originates from a landline with an area code like 03 or 06, or a mobile number starting with 090 or 080.
According to Japan's Ministry of Internal Affairs and Communications, tens of thousands of consultations about anonymous calls are filed each year, and many people feel anxious about them. Installing a phone with anonymous call blocking can also be effective. This article covers everything from why anonymous calls happen to specific countermeasures, carrier-specific settings, and how to report them to police.
Why You Receive Anonymous Calls
Legitimate Reasons for Withholding Caller ID
Some businesses automatically withhold their number due to PBX (Private Branch Exchange) settings. Hospitals contacting patients or government agencies calling for official purposes may also use anonymous calling. Individuals sometimes choose to withhold their number for privacy. Job-related calls from prospective employers or callbacks from real estate agents are common everyday examples. On NTT landlines without the Number Display service, numbers may not appear at all, which can be confused with anonymous calls.
Malicious Anonymous Calls
Anonymous calls are also used for stalker harassment, prank calls, and as a precursor to fraud - for example, checking whether someone is home. Late-night or early-morning anonymous calls are especially likely to be harassment and can cause significant psychological distress. According to the National Police Agency, organized fraud groups frequently use anonymous calls to confirm targets' availability. Silent calls are also linked to this pattern; if you receive repeated anonymous calls with no one speaking, robocalls may be involved.
Basic Ways to Handle Anonymous Calls
There are several options depending on your situation. The safest response is simply not to answer, though some people may need to pick up for work-related reasons. Here is a summary of approaches:
- Enable anonymous call blocking: Your smartphone or landline can automatically reject anonymous calls. This is the most reliable measure.
- Use Number Request service: NTT offers a service that plays an automated message asking anonymous callers to redial with their number displayed. It costs 220 yen per month.
- Let voicemail handle it: Do not answer anonymous calls and let voicemail pick up. Legitimate callers will leave a message.
- If you must answer, never share personal information: Do not reveal your name, address, or date of birth. Ask "Who is calling?" to verify the caller's identity first.
- Record the call: Use a call recording app to preserve evidence of threats or harassment. In Japan, recording a call you are a party to is legal.
How to Block Anonymous Calls by Device
iPhone (iOS)
On iPhone, go to Settings > Phone > Silence Unknown Callers and turn it on. This silences calls from numbers not in your contacts, including anonymous calls, and sends them directly to voicemail. Note that this also silences calls from any unregistered number.
Android
On Android, open the Phone app settings, go to Blocked Numbers, and enable "Unknown callers." The exact menu names may vary by manufacturer, but the basic steps are the same.
Landline Phones
For NTT landlines, subscribing to the "Number Request" service automatically rejects anonymous calls. The same service is available for Hikari Denwa (fiber-optic phone). Many phone handsets also have built-in anonymous call rejection - check your manual to enable it.
What to Do About Repeated Anonymous Calls
If anonymous calls keep coming, there may be stalking or harassment involved. Use a spam call blocking app and follow these steps:
- Save your call log: Record the date, time, frequency, and content (if you answered) in detail. Screenshots and call recordings are valuable evidence.
- Contact the police: Visit the Community Safety Division at your nearest police station. For non-emergencies, you can also call the police consultation line at #9110.
- Request protection under the Anti-Stalking Act: Japan's Anti-Stalking Act covers phone harassment as a form of "pursuit." Police can issue a warning to the perpetrator, and if ignored, a restraining order can follow.
- Consider changing your number: If call blocking is not enough, contact your carrier to arrange a number change.
Laws and Rights Regarding Anonymous Calls
Making an anonymous call is not illegal in Japan by itself. However, repeated anonymous calls as harassment may violate the Anti-Stalking Act or local nuisance prevention ordinances. Article 2 of the Anti-Stalking Act specifically covers "making calls without speaking, or repeatedly calling despite being refused." Violations carry penalties of up to one year in prison or a fine of up to one million yen. A 2021 amendment also added GPS-based location tracking to the list of regulated behaviors, strengthening protections against combined stalking tactics.
Fraud committed via anonymous calls falls under the Penal Code's fraud provisions (Article 246) and can result in up to 10 years in prison. If you are a victim, do not give up - consider pursuing legal remedies.
Common Misconceptions About Anonymous Calls
"All anonymous calls are dangerous"
Not every anonymous call is malicious. As noted above, PBX settings, official business, and personal privacy are all legitimate reasons. Calls from prospective employers, hospital test results, or law firm callbacks are everyday examples. Blocking all anonymous calls indiscriminately may cause you to miss important communications.
"The source of an anonymous call can never be traced"
While ordinary individuals cannot trace anonymous calls, police with a warrant can compel carriers to disclose the caller's identity. In stalking and threat cases, perpetrators have been identified and arrested through police investigations. Do not assume the caller will never be found - preserve evidence and consult the police.
Protecting Seniors from Anonymous Call Scams
Elderly people are the primary targets of phone fraud, making anonymous call countermeasures especially critical. According to the National Police Agency, roughly 80% of phone fraud victims are aged 65 or older. Family members should set up their elderly relatives' phone environments to prevent victimization.
- Install a phone with automatic recording warnings: Phones that play "This call is being recorded" deter scammers. Some municipalities offer subsidies for purchasing these devices.
- Use nuisance call prevention devices: Police and local governments lend out free devices that play warning messages and automatically record calls. See also how to block nuisance calls.
- Establish a family code word: Agree on a secret phrase to verify identity when someone calls asking for money.
- Use voicemail even when home: Screen calls through voicemail and call back after checking the message. Scammers rarely leave messages.
Summary - Protecting Yourself from Anonymous Calls
Dealing with anonymous calls comes down to proactive settings and calm responses. Enable anonymous call blocking, and if you must answer, never share personal information - this is fundamental to phone number privacy. Repeated anonymous calls may constitute a crime, so preserve evidence and consult the police. Do not face this alone; seek help from the appropriate authorities.