How to block spam calls on iPhone: a step-by-step guide

Unwanted marketing calls and phone scams have become a daily nuisance, and the iPhone comes with several tools to fight back. In this guide we go through iOS's native settings, the "Silence Unknown Callers" feature and caller-ID apps, along with their real-world limits. The aim is for you to come away knowing exactly what to tap and what to expect from each option.

Blocking a specific number from the Phone app

When a particular number is harassing you, the most direct fix is to block it from your call log. It's the ideal solution for that number that rings several times a day.

1. Open the Phone app and go to the Recents tab.
2. Find the call from the number you want to block and tap the info button (the (i) icon on the right).
3. Scroll to the bottom of the card and tap Block this Caller (or Block Contact if you've saved it).
4. Confirm the action.

From that point on, calls, messages and FaceTime from that number are silenced. Nothing rings and the number goes straight to voicemail if it keeps trying.

You can review and manage your list under Settings → Phone → Blocked Contacts. From there you can also add numbers manually or remove blocks you no longer need.

The problem with blocking one by one

Blocking individual numbers works, but it has an obvious weak spot: spammers change numbers constantly. Today you block one and tomorrow they call you from another almost identical one. That's why, for mass spam campaigns, it's worth combining it with the options we look at below. If you want a full overview of every technique, we recommend our guide to blocking spam calls.

"Silence Unknown Callers": the automatic iOS filter

iOS includes a feature that automatically silences any call from a number that isn't in your contacts. It's one of the most effective defences against spam, but you need to understand exactly how it works before turning it on.

To enable it:

1. Go to Settings → Phone.
2. Find and tap Silence Unknown Callers.
3. Turn the switch on.

What it does exactly

When it's on, this feature sends to voicemail every call from numbers you haven't saved, that don't appear in your recent emails or outgoing messages. The phone doesn't ring: the call shows up in Recents as a missed call and, if the caller leaves a message, you'll see it in your voicemail.

iOS is smart enough not to block someone you've just interacted with. If you've sent an email or a message to a number, or if Siri recognises the contact from your activity, that call can still ring even if you don't have it saved.

The side effect you need to know about

This feature is blunt, and that's its biggest drawback: it also silences legitimate calls from unknown numbers. That includes the delivery driver who can't find your door, the doctor's surgery confirming an appointment, a job interview or the technician coming to your home. All of those calls will go to voicemail without alerting you in real time.

That's why it's worth checking your voicemail and Recents log fairly often if you turn this option on. It's a trade-off: you gain peace of mind against spam in exchange for not receiving legitimate calls from unknown numbers instantly. For many people it's worth it; for those who expect important calls from strangers (freelancers, sales reps, etc.) it can be too restrictive.

Caller-ID and call-blocking apps

iOS doesn't identify on its own who's behind an unknown number, but it lets third-party apps do so through what's called the Call Directory extension. These apps maintain databases of numbers flagged as spam and "lend" them to the system so iOS can show a label or block the call before it rings.

To enable one of these apps, once installed:

1. Go to Settings → Phone.
2. Enter Call Blocking & Identification (the name may vary slightly depending on your iOS version).
3. Turn on the switch for the app you want to use as a source of identification or blocking.

With the extension active, when a call comes in from a number flagged in its database, you'll see a label such as "Suspected Spam" or the company's name, and it may even be blocked automatically. The big advantage over manual blocking is that the database is updated with numbers reported by the whole community, so it covers numbers you'd never seen before.

If what you care about most is knowing what you're dealing with before you pick up, we have a dedicated guide on how to find out who's calling you that goes deeper into this topic.

The iOS limitations worth accepting

It's worth being realistic about what iOS can and can't do:

• Blocking is by number, not by person or company. If the spammer rotates numbers (which is common), you'll have to block each one or rely on a caller-ID app.
• iOS doesn't identify on its own. Without a third-party app with a Call Directory extension, an unknown call just appears as a number, with no context.
• "Silence Unknown Callers" is all or nothing. You can't create fine-grained exceptions beyond your contacts and the recent interactions the system recognises.
• Blocking doesn't stop someone leaving a voicemail. A blocked number can still leave a message in a separate section of your voicemail; your phone simply doesn't ring.

What to do if they still call you

No method is foolproof, so it's worth having a routine when spam slips through:

1. Block the number on the spot. From Recents, tap (i) and block it. Every number blocked is one less.
2. Don't pick up if you don't recognise it. Answering confirms to automated diallers that your line is active, which usually brings more calls. Let it go to voicemail.
3. Report it. Reporting the number in a community database helps other people get a warning before they pick up. You can look up and report numbers in our spam number directory.
4. Sign up for the Robinson List. It reduces marketing calls from companies that respect the advertising opt-out register. It doesn't stop scams or anyone who ignores the law, but it cuts down the legal noise. We explain how in the Robinson List guide.
5. Check your voicemail if you use "Silence Unknown Callers". So you don't miss a legitimate call, glance at Recents and your voicemail once or twice a day.

In summary

The iPhone gives you three layers of defence that work best combined: manual blocking for specific repeat offenders, "Silence Unknown Callers" as a general filter (accepting that legitimate unknown calls will go to voicemail) and a caller-ID app with a Call Directory extension to put a name and label on whoever's calling. With those three elements active, most phone spam stops bothering you.

Want to know who's behind a number and warn everyone else? Identify and report suspicious calls with NoCall in our spam number directory and help the community get there before the scammers.