In short. You can reject withheld-number calls: on iPhone with Silence Unknown Callers (Settings → Apps → Phone), on Android with the call filtering features of Google's Phone app, and with some carriers through an anonymous-call rejection service. But be careful: none of these filters has any effect on text messages. A message still gets delivered even when a call from the same sender is rejected.
Information verified on 25 October 2026 on the public pages of Arcep, the CNIL, service-public.fr, Légifrance, the 33700 scheme (AF2M) and on the public support pages of Apple, Google and the French carriers. This article provides general information and does not replace the advice of a lawyer.
Why have you been getting more withheld-number calls since 2026?
Because the rules on displaying the calling number have changed. Since 1 January 2026, French carriers have been required to cut off calls whose displayed number cannot be authenticated — a mechanism described by Arcep under the name MAN (mécanisme d'authentification des numéros, number authentication mechanism), provided for by the law of 24 July 2024 aimed at reducing the environmental footprint of digital technology and, above all, by the anti-fraud regulations detailed on service-public.fr in December 2025.
The very concrete consequence, widely commented on in early 2026: rather than risk having their calls cut off, some professional callers — offshore call centres, platforms using non-authenticatable numbers, internal company services — no longer display any number at all. The call goes through, but it arrives as "Withheld number", "Unknown" or "Private".
So you need to distinguish between three things that phone screens tend to blur:
- Withheld number / Private: the caller has deliberately suppressed the presentation of their number (the
#31#prefix, a handset setting, a carrier option). The number exists and remains in the carrier's logs. - Unknown number / Unavailable: the presentation could not be transmitted (interconnection issues, calls from certain foreign networks, a badly configured switchboard).
- Number not in your contacts: a real number is displayed, you simply haven't saved it. This is not a withheld call, and yet many filters treat it as one.
This distinction decides everything: some settings block only the first category, others block all three. Picking the wrong one means missing a callback from a doctor, a recruiter or a delivery driver.
How do you block withheld-number calls on iPhone?
Apple does not offer a filter specifically targeting "withheld numbers". The available feature is Silence Unknown Callers, which sends straight to voicemail any call coming from a number that isn't in your contacts, your recent outgoing calls or Siri Suggestions.
- Open Settings.
- Go to Apps → Phone (on iOS 18 and earlier: Settings → Phone).
- Tap Silence Unknown Callers.
- Turn the option on.
Since iOS 26, Apple has extended the system with Call Screening, which has the system ask for the caller's name and the reason for the call before the phone rings, and displays the answer on screen. The details and availability by country and language are described on the Apple support page "Block unwanted calls and contacts".
What you should know before turning it on:
- filtered calls do not ring but do appear in your recent calls and can leave a voicemail;
- emergency calls and recent callbacks remain prioritised;
- a determined caller who knows your number will switch to text messages, entirely outside the scope of the feature.
If you work heavily by phone and are worried about missing a legitimate call, the common compromise is to turn screening on and keep an eye on visual voicemail rather than listening out for the ringer. A noise-cancelling Bluetooth headset is useful here less for comfort than to avoid missing the transcription alert when you're out and about.
How do you filter withheld-number calls on Android?
On Android, everything depends on the Phone app installed by the manufacturer. The most widespread one, Phone by Google, offers a dedicated setting:
- Open the Phone app.
- Tap the ⋮ icon (or your profile picture) → Settings.
- Go to Withheld numbers or Call filtering, depending on the version.
- Turn on Calls from withheld numbers (and, if you wish, Calls from unknown numbers).
Manufacturer skins differ: on Samsung, the path runs through Phone → ⋮ → Settings → Block numbers, with a Block unknown/private numbers checkbox. On Xiaomi, the setting is found under Security → Call blocking.
Two limits to keep in mind:
- a call blocked by the Phone app has already been routed by the network: it appears on the caller's itemised bill and in the carrier's logs, which matters if you file a complaint;
- filtering doesn't stop the caller from learning that the line exists, since the ringing is simulated on the network side.
For anyone who changes numbers often or manages a separate work line, the simplest approach remains the second number: we explained how eSIMs and secondary lines work in our guide on the secondary number for discreet messaging. A dual-SIM adapter doesn't really exist, but an eSIM-compatible phone settles the question without a second device.
What do Orange, SFR, Bouygues Telecom and Free Mobile offer?
Network-level rejection of anonymous calls does exist, but the offering has shrunk over the years and is not consistent. The table below summarises the situation as it appears on the carriers' public support pages as of 25 October 2026; always check the page for your own plan, as options change without notice.
| Carrier | Anonymous call rejection | Where to find it | Effect on text messages |
|---|---|---|---|
| Orange | Filtering service offered on mobile and landline depending on the plan | Customer account / "unwanted calls" support | None |
| SFR | Call blocking options depending on the plan, often via the app | SFR & Moi app → call management | None |
| Bouygues Telecom | Unwanted call filtering depending on the plan | Customer account → line services | None |
| Free Mobile | No general option to reject withheld-number calls on mobile | Use the phone's own settings instead | None |
The right-hand column is the most important in this whole article: no anonymous call rejection service filters text messages. Calls and short messages travel different paths through the network, and "number presentation" is a voice telephony function. That is exactly why the #31# prefix has no effect on a text message — a point we explained in our article on how to call back a withheld number without revealing your own.
Can you block text messages coming from a withheld number?
No, because a text message is never "withheld" in the sense that a call is. A short message always arrives with a sender identifier: a mobile number, a short code (such as 38xxx), or an alphanumeric sender (a brand name instead of a number). There is no equivalent of #31# that would simply strip out that identifier.
What you can do, on the other hand:
- Block the sender in the Messages app (iPhone: tap the name at the top of the conversation → Info → Block this Caller; Android/Google Messages: long-press the conversation → Block).
- Filter unknown senders: on iPhone, Settings → Apps → Messages → Filter Unknown Senders puts messages from strangers in a separate tab, with no notification.
- Report to 33700 by forwarding the message: the scheme run by AF2M handles unwanted and fraudulent text messages, and replies asking for the sending number.
- Report criminally punishable content on the Pharos platform (internet-signalement.gouv.fr), or file a complaint.
An alphanumeric sender is a special case: it doesn't allow a reply and cannot be "called back". We described what you can and cannot infer from it in the article devoted to identifying the sender of an anonymous text message.
What does the law say when calls or messages become persistent?
Filtering is a convenience; the law takes over when repetition turns into harassment. Article 222-16 of the French Criminal Code punishes "repeated malicious telephone calls, the repeated sending of malicious messages by means of electronic communications, or acoustic aggression" intended to disturb another person's peace. The full text can be consulted on Légifrance.
Three practical consequences:
- Don't delete anything. Messages that have been kept, time-stamped, with the number or displayed identifier, form the foundation of the case file. Our guide on building solid evidence when faced with an anonymous text message sets out the capture method.
- You will not be able to identify the caller yourself. No consumer service and no "reverse directory" app can unmask a withheld number. Only a judicial order served on the carrier, as part of an investigation, can obtain the identity of the line's subscriber. Traffic data retention periods are governed by the French Post and Electronic Communications Code and recalled by the CNIL.
- Filing a complaint is free and can be prepared online. The "violence and harassment" page on service-public.fr explains the steps to follow; cybermalveillance.gouv.fr publishes useful quick-reference sheets.
A well-configured filter protects your peace and quiet. It does not protect your case file: these are two different jobs, and the second one requires keeping records rather than erasing them.
For anyone keeping a log of incidents — dates, times, contents — a hardcover notebook remains, as archaic as that may sound, more robust in front of a police officer than an app note wiped out by an update.
How can you filter without missing the calls that matter?
The real risk of blanket blocking isn't technical, it's social: hospitals, schools, police services, doctors' surgeries and company switchboards very often call from withheld or unsaved lines. Here is a balanced setup.
- Systematically save the numbers you need: your GP, the school, the building manager, your employer, your bank's customer service. That's the condition for "Silence Unknown Callers" to remain liveable.
- Turn filtering on only during sensitive periods: iOS Focus modes and Android's Do Not Disturb modes allow scheduled activation, with exceptions for favourite contacts.
- Let voicemail do the sorting. A legitimate call leaves a message in 90% of cases; a cold call rarely does. Check the transcription rather than answering.
- Keep a second number for forms. Giving out your main line with every sign-up is what feeds the flood. We developed this point in this article on the phone number that has become a national ID.
- Register with Bloctel if the nuisance comes from commercial cold calling. The service is free and run under the authority of the DGCCRF; it does not cover fraudulent calls or personal messages.
On the hardware side, two purchases often prevent clumsy workarounds. A no-contract prepaid SIM card lets you isolate a "forms" line without touching your main subscription. And for those who still keep a landline, a landline phone with built-in call blocking filters withheld numbers at device level, without depending on a carrier option — useful for older people, the first targets of persistent cold calling.
What a filter will never do
- It doesn't reveal the number. A rejected call remains an anonymous call as far as you're concerned.
- It doesn't stop you being contacted through another channel: SMS, RCS, WhatsApp, Signal, email.
- It doesn't erase the trace on the network side. That's good news: traffic data exists and can be obtained by judicial order.
- It is not the same as filing a complaint. Blocking and then staying silent leaves the perpetrator free to start again from another line.
If the situation involves a minor, the logic is different and the priority is dialogue before technology: we set this out in detail in the article on anonymous text messages received by a teenager.
Frequently asked questions
Does #31# block text messages too?
No. The #31# prefix suppresses the presentation of your number for a voice call only. Dialled in front of a number in the Messages app, it has no effect: the text goes out with your number, or isn't sent at all.
Can you find out who is calling from a withheld number?
Not on your own. No reverse directory app can unmask a withheld presentation. Only a judicial order served on the carrier, as part of an investigation or a complaint, can obtain the identity of the line's subscriber.
Is blocking a withheld number legal?
Yes, completely. You are free to refuse any incoming call you choose. No obligation requires you to pick up, including for a professional or administrative call.
Why have I been getting more withheld-number calls since January 2026?
Because the mandatory authentication of calling numbers, which came into force on 1 January 2026, leads some callers whose number cannot be authenticated to withhold the presentation rather than have the call cut off by the carrier.
Does filtering unknown calls block emergency services?
No, not for callbacks from emergency services following an outgoing call on your part, which remain prioritised on both iPhone and Android. However, a hospital or school calling for the first time from a withheld switchboard number may be filtered: save those numbers in advance.
Updated on 25 October 2026. The settings paths correspond to iOS 26 and to the September 2026 version of Phone by Google; they may vary depending on the manufacturer and version. To send a message without revealing your number, see the site's sending page and our use cases.
