Nuisance calls have stopped being an annoyance and become a real safety issue. UK Finance recorded over £600 million stolen by fraudsters in the first half of 2025 alone, and a growing share of those losses begin with a single unsolicited phone call. The most effective defence against the next one is also the simplest: stop the call from reaching you in the first place.
This guide walks through how to silence, screen and block unknown callers on both iPhone and Android, using the tools built into each phone. No third-party apps, no subscriptions. Every feature below ships with the operating system. Settings menus differ slightly between manufacturers and versions, so where it matters, the instructions cover the most current behaviour in 2026.
iPhone: Silence, screen, or block
Apple has steadily expanded its anti-spam tools over the past few releases, and with iOS 26 there are now three distinct ways to handle calls from numbers you don’t recognise. Each takes less than a minute to set up.
Silence Unknown Callers
This is the blunt-instrument approach. Anyone who is not in your Contacts, has not been called by you recently, or has not been suggested by Siri based on emails or messages will be sent straight to voicemail. The call still appears in your Recents list, and the caller can leave a message if they wish, but your phone never rings.
To turn it on, open Settings, tap Apps, then Phone, and scroll to Screen Unknown Callers. Choose Silence.
The trade-off is honest: you will miss the occasional legitimate call from a delivery driver, a hospital appointment line, or a tradesman calling back. For many older users, that trade-off is well worth making, particularly if family members can be warned to leave a voicemail.
Ask Reason for Calling (iOS 26)
The newer middle option, introduced with iOS 26, is the most useful feature Apple has added to the Phone app in years. Instead of silencing unknown callers outright, the phone answers automatically with a synthetic voice that asks the caller to state who they are and why they are calling. Their answer is transcribed on-screen in real time.
If it’s your dentist confirming an appointment, you can swipe to answer. If it’s a recorded sales message or someone pretending to be from “your bank’s fraud department,” you can let it go to voicemail without ever picking up.
In the same Screen Unknown Callers menu, choose Ask Reason for Calling.
Scam autodiallers and pre-recorded robocalls typically fail this step entirely. They either hang up or play their script into the void, while real people identify themselves and the call comes through.
Block a specific number
If a particular nuisance number keeps phoning, you can block it permanently. Open the Phone app, tap Recents, find the call, and tap the small i icon next to the number. Scroll to the bottom and tap Block this Caller, then confirm.
Blocked numbers cannot call, text, or FaceTime you. To review or remove blocked numbers, go to Settings › Apps › Phone › Blocked Contacts.
Filter and report spam
iPhone also offers a separate Call Filtering option in the Phone settings. Turning on Unknown Callers here moves missed calls and voicemails from unsaved numbers into a dedicated list, keeping your main Recents tab uncluttered. Calls flagged as spam by your carrier are silenced and routed to a separate Spam list.
One caveat worth knowing: Silence Unknown Callers automatically switches off for 24 hours after a call to 999 or 911, so emergency services and follow-up callbacks can always get through.
Android: Pixel, Samsung, and everything else
Android does the same job, but the route to the settings depends on which manufacturer made the phone. The three most common are Google Pixel, Samsung Galaxy, and “everyone else” running a near-stock version of the Phone by Google app.
Google Pixel: Call Screen and Caller ID & Spam
Pixel phones have the most sophisticated screening features of any Android handset, powered by Google’s on-device AI.
To set up Call Screen, open the Phone app, tap the three-dot menu in the top right, choose Settings, then Spam and Call Screen (on newer models) or Call Screen. Tap Unknown call settings and pick how each category of caller is handled:
- Spam: automatically declined
- Possibly faked numbers: silenced or screened
- First-time callers: screened
- Private or hidden: declined
You can also turn on Automatically screen calls. When an unknown number rings, Google Assistant answers, asks the caller who they are, transcribes the reply, and lets you decide whether to pick up.
For broader spam filtering, in the same Settings menu turn on Caller ID & spam. This uses Google’s database to label likely scam calls before they ring.
Samsung Galaxy: Smart Call
Samsung phones running One UI have their own equivalent, called Smart Call.
Open the Phone app, tap the three-dot menu, choose Settings, then scroll to Caller ID and spam protection. Toggle the switch at the top to enable it. Samsung will then check incoming numbers against a known-spam database and warn you on screen when a call is suspected to be unwanted.
To send all unknown numbers straight to silent, look for Block unknown/private numbers in the same menu. The exact wording varies by One UI version, but the option is consistently in Settings › Block numbers.
Block a specific number on Android
The fastest method on virtually any Android phone is identical to the iPhone approach.
Open the Phone app, tap Recents, tap the offending number, then tap the i info icon (or the number itself, depending on the manufacturer). Scroll down and tap Block or the circle-with-a-slash icon, and confirm.
To review your blocked list, go to Phone › menu › Settings › Blocked numbers. From the same screen you can add numbers manually if you have been called by someone whose number you never want to see again.
Block unknown and withheld numbers entirely
On most Android handsets you can refuse every call from a withheld or private number with one toggle. The setting lives in Phone › Settings › Blocked numbers and is usually labelled Unknown or Block calls from unidentified callers. Turning it on means anyone deliberately hiding their number will be declined automatically.
A few practical notes
The right level of aggression depends on the user. A retired person who rarely receives calls from unknown numbers can switch on Silence Unknown Callers without a second thought. Someone running a small business will want the gentler Ask Reason for Calling option on iPhone, or Pixel’s Call Screen, so they don’t lose a customer enquiry.
It’s worth pairing the phone-level settings with two free services that work in the background. Registering a UK number with the Telephone Preference Service at tpsonline.org.uk is the legal opt-out from unsolicited sales and marketing calls. And forwarding suspicious text messages to 7726 sends them to your mobile network for investigation, which feeds the spam databases your phone is already consulting.
Before you block a number outright, it can also be worth running it through a scam-call lookup directory. If other people have already flagged the same number as fraud, that confirms your instincts, and your own report adds another data point for whoever gets called next.
Finally, if the same number keeps phoning after you’ve blocked it, particularly if it’s pretending to be your bank, HMRC, or the police, report it. Action Fraud (0300 123 2040) takes reports from victims directly, and scam-call lookup directories build up a picture of which numbers are causing real harm. Every report makes the next person’s phone a little quieter.
Blocking is not a silver bullet. Scammers spoof caller ID and rotate through fresh numbers daily. But every layer you add (silencing, screening, blocking, reporting) makes it harder for the next nuisance call to land at the worst possible moment.