How to Block Spam Calls on iPhone: Silence Unknown Callers, Call Screening and Carrier Labels

Layer 1: block a number

Open the Phone app, go to Recents, tap the (i) next to the call, scroll down and tap Block this Caller. Blocked callers cannot call, FaceTime or message you; on most carriers the call goes straight to voicemail without ringing, and the voicemail (if any) is filed under a separate Blocked Messages folder so you never have to see it. You can review or remove blocks under Settings → Phone → Blocked Contacts (the menu lives under Settings → Apps → Phone on recent iOS versions).

Blocking one number is the right tool for a persistent individual caller — an ex-employer's payroll robot, a pharmacy line you no longer use — and the wrong tool for robocall campaigns, which rotate through hundreds of numbers. If the same campaign keeps arriving from different numbers, move on to the next layers. Before blocking, a quick lookup tells you what you are dealing with: a number with a trail of FTC Do Not Call complaints is a campaign; a clean local number is probably a person.

Layer 2: Silence Unknown Callers

Settings → Phone (or Settings → Apps → Phone) → Silence Unknown Callers. When it is on, any call from a number that is not in your Contacts, not in your recent outgoing calls and not suggested by Siri from your mail or messages is silenced: it goes to voicemail, appears in Recents, and never rings. Everyone you know still gets through; everyone you don't leaves a message.

It is blunt, and that is why it works — robocall systems rarely leave voicemail, and the ones that do are easy to delete unheard. The cost is that a legitimate first-time caller (a clinic confirming an appointment, a delivery driver at the gate, a recruiter) also goes to voicemail. Two things reduce the pain: save numbers you are expecting to hear from before they call, and turn on Live Voicemail (Settings → Phone → Live Voicemail, iOS 17 and later), which transcribes the message on screen in real time so you can pick up mid-message if it is someone you want.

Silence Unknown Callers is per phone, not per line, so it also works on prepaid plans and small carriers that have no network-level filtering of their own.

Layer 3: screen unknown callers (iOS 26 and later)

iOS 26, released in September 2025, added a middle path between ringing and silencing. Under Settings → Apps → Phone → Screen Unknown Callers you can choose Ask Reason for Calling: when a number not in your contacts calls, the iPhone answers it silently, asks the caller to say their name and why they are calling, and only then rings you — with the transcribed answer on screen so you can decide to pick up, ignore or reply. Robocall systems, which expect a human to say "hello", almost never survive the prompt; the call simply ends. Real people state their business and get through.

The same menu keeps the older options — Never (let everything ring) and Silence (the Layer 2 behavior). If you find Silence Unknown Callers too aggressive because too many legitimate first-time callers land in voicemail, screening is the setting to try instead. It is also the closest thing iPhone has to Google's Call Screen on Pixel phones.

Screening runs on the device, so it does not depend on your carrier and does not send audio to Apple. The caller's spoken reason is shown to you as text, and the call is logged normally.

Layer 4: carrier labels and call-identification apps

Your carrier scores calls in its network before they reach your iPhone, and the verdict shows on the incoming-call screen: "Potential Spam" on Verizon, "Spam Risk" on AT&T, "Scam Likely" on T-Mobile. The carriers' apps — Verizon Call Filter, AT&T ActiveArmor, T-Mobile Scam Shield — add blocking of whole categories and personal block lists, and all three are free at the basic tier. Each has its own guide here: Verizon, AT&T, T-Mobile. After installing a carrier or third-party app, go to Settings → Phone → Call Blocking & Identification and switch it on; iOS will not let an app label or block calls until you do, and this is the step most people miss.

Third-party apps (Hiya, Nomorobo, RoboKiller, Truecaller and others) work through the same Call Blocking & Identification framework, matching incoming numbers against their databases on the device. Apple's support article on detecting and blocking spam calls with third-party apps explains the mechanism. Most have a free tier and a subscription; the free carrier app usually gets you 80% of the benefit because it sees the network-level signals the third parties do not.

A verified checkmark next to a caller's number (or "Caller Verified" text) means the call passed STIR/SHAKEN caller-ID authentication — the carrier that originated the call vouched that the caller is entitled to use the number. It is a good sign but not a guarantee the call is wanted; an authenticated telemarketer is still a telemarketer. The absence of the checkmark is not proof of spoofing either, since many small carriers still do not sign calls. The FCC's call authentication page has the details.

Texts, Focus modes and the calls that still get through

For junk texts: Settings → Apps → Messages → Filter Unknown Senders moves messages from numbers not in your contacts to a separate list, and Report Junk (the link under a message from an unknown sender) deletes it and reports it to Apple and your carrier. Forwarding a spam text to 7726 (SPAM) reports it to your carrier's filters on all three major networks. Do not reply, not even STOP — for scam texts that just confirms a live number.

Focus modes (Settings → Focus) let you allow calls only from Contacts, Favorites or a chosen group during sleep or work, with an option to let repeated calls from the same number within three minutes through — that exception is how a genuine emergency still reaches you.

Finally, the two steps that work regardless of phone: register at the National Do Not Call Registry so that lawful telemarketers must stop calling within 31 days, and report the calls that keep coming at DoNotCall.gov or ReportFraud.ftc.gov. The FTC publishes those complaints every weekday; they are the reason a number page on this site can tell you a caller has 300 complaints this month before you ever pick up.

Sources

1. Apple Support — Detect and block spam phone calls with third-party apps
2. FCC — Caller ID authentication (STIR/SHAKEN)
3. FTC — National Do Not Call Registry

Related

• Block spam calls on Android
• What 'Spam Risk' means
• What 'Scam Likely' means
• How to stop robocalls
• "Wrong number" text scam

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