How can I block phone numbers on my iPhone? Can I block nuisance callers' numbers in iOS 6, or is it only possible in iOS 7 and later?

Nuisance calls are the bane of the modern age. Fortunately you can block specific callers (or rather, specific phone numbers), enabling you to avoid them safely without having to cut yourself off from the people you want to talk to.

Until recently the iPhone didn't offer a straightfoward way to block an incoming number: it could be done, but it involved complicated workarounds or jailbreaking. But that all changed with the introduction of Apple's iOS 7 operating system for iPhoneiPad and iPod touch. (iOS 8 retains the simple number-blocking features of iOS 7; as does iOS 9, expected to launch officially in September 2015.)

In this tutorial we show how to block an unwanted caller's number on an iPhone, whether it's an iPhone 6 Plus, iPhone 6iPhone 5s, iPhone 5ciPhone 5, iPhone 4S or an earlier model - even the iPhone 3GS, which can't run iOS 7. 

We show how to set up a call block in iOS 7 and later (which is easy) and in iOS 6 and earlier (which is more difficult). Then we look at some more advanced methods of blocking callers who know to hide their caller ID in an effort to get round the standard call-blocking procedure. Last of all, we explain how to find out if someone has blocked your number.

Jump to the section that applies to you:

How to block a number in iOS 7

How to block numbers on an iPhone in iOS 7 and later

Let's start with the easier task. Blocking a nuisance caller's phone number in iOS 7 (and iOS 8 and iOS 9) is simple.

Say you receive a call, hang up (or don't answer), and then decide you want to block that person's number and avoid being bothered in the future.

Simply go to your list of recent callers (from the Home screen you can open the Phone app, then clock on the Recents tab at the bottom). Click the 'i' symbol next to the unwanted number, then scroll down to the bottom of the resulting screen and clock Block this Caller, then confirm your decision. You won't be bothered with any calls, texts or FaceTime link-ups from that number.

(When we tried calling an iPhone that had blocked us, we heard a single ring, and were then diverted to the O2 messaging service, where we recorded a message. But the iPhone didn't ring, or show the number in its recent calls, and we couldn't find any new voicemail.)

How to block a number in iOS 7

We didn't appreciate being contacted by that blurred-out number at the top, so let's block it. Click the 'i' to the right of the number and we'll see this screen (scroll down to the bottom):

Block a phone number in iOS 7

Alternatively, go to the Settings app and scroll down to the Phone section. Scroll down again and click Blocked, and you'll see your list of blocked callers. Hit Add New and pick further numbers to block from your contacts list. (You'd need to add the nuisance caller to your contacts list for this method to work, however.)

How to block a number in iOS 7

Read next: How to block and report iMessage spam

How to unblock numbers on an iPhone in iOS 7, iOS 8 and iOS 9

The second method comes into its own when we reverse the decision. Go to Settings, Phone, Blocked and hit Edit. Click the red circle next to the blocked number you want to unblock, and a red button will appear. Press that.

How to block a number in iOS 7

Alternatively - and more helpfully if you change your mind right away - you can simply tap the 'Block this caller' option again, after clicking the 'i' symbol next to a recent number (it changes to 'Unblock this caller' when you block them).

Read next: iPhone 6s review | iPhone 6s Plus review | All iPhone reviews

Can I block a number on an iPhone in iOS 6 or earlier?

The advice we'd offer first of all is to update to the latest version of iOS (iOS 8 at present, although iOS 9 will be with us soon) - this is a free process and brings numerous useful features. However, some devices simply can't run iOS 8. Any iPhones before the iPhone 4 are incompatible.

So ok - let's say you're sticking with iOS 6. You can still block a number on an iPhone in iOS 6, but it's a lot trickier. If you don't want to put up with problem callers and aren't willing to update to iOS 7, there are two techniques you can use to block nuisance callers on your iPhone. (A third technique would be to change your number, sadly.)

1. Jailbreak your iPhone, and block numbers using iBlacklist or another unofficial app

'Jailbreaking' your iPhone means bypassing the locks put in place by Apple to prevent unauthorised apps being used on the phone. Once your break these restrictions, you gain access to a large number of unofficial apps, many of which offer features you'd never otherwise be able to access; but jailbreaking is legally ambiguous, risky, and certain to void any warranties you have with Apple. Therefore our advice is to think long and hard before going ahead with the jailbreaking process. (What's more, the known methods for jailbreaking the iPhone 4S and later won't work if you've updated to iOS 6.1.3 or later, so you'll have to jump ahead to solution 2.)

If you decide to jailbreak your iPhone (and have heard and understood our warnings), we have full iPhone jailbreaking instructions here. As we said, you'll need to be using iOS 6.1.2 or earlier to achieve a long-term jailbreak - the most recent updates fixed the flaw that allowed the process to work. (iOS 7 hasn't been jailbroken yet, incidentally, but we expect it will be soon.)

iBlacklist Cydia app

Once you've jailbroken your iPhone, you need to find a call-blocking app. Search on the Apple App Store and the independent Cydia app store. The blocking app we are going to use is called iBlacklist, which is on Cydia. It costs $12.99 (about £8.50) and offers the ability to block calls and SMS messages from specific numbers, as well as all unknown numbers.

Install iBlacklist, restart your iPhone, open iBlacklist and click 'Blacklists'. To add a phone number to your blacklist, hit 'Add new Blacklist' and add it manually (you can do this via your recent call list). Once you've added a number, set the 'Call' icon to 'On'. To block text messages do the same thing with the 'Message' icon.

Now you need to configure what happens when a call comes in from a blacklisted number. Hit 'Action to be performed'. Options include blocking before your phone even acknowledges the call, sending back the engaged tone, sending the caller directly to voicemail, or automatically hanging up the call. Finally, hit the blue button to save your selections and that number is blocked.

2. Set up an 'unwanted caller' contact

That was the nuclear option, and certainly the most effective. However, we don't much like the idea of jailbreaking our iPhones, so we prefer this canny workaround.

Create a contact from the number you were called on. Instead of naming it after the person or company, however, call the contact 'Nuisance Caller', 'Hang Up' or some other label that you'll understand. When it comes up you'll know that it's an unwanted caller, and won't pick up.

How to block a number on an iPhone 5

Unwanted caller iPhone Contact

It may look like I'm calling my 10-week-old son an idiot, but I'm not! Poor little chap.

And it doesn't just work on one number. Every time a different timewaster calls you, simply bring up the recent calls screen, tap the arrow by the number and hit 'Add to Existing Contact'. Then add them to the previously created contact.

But wait: it gets better. To save you the trouble of looking at your phone to see who's calling, you can set a specific ringtone to the troublemaker contact. The robot, say, or the quacking duck. Better still, you can set it to a silent ringtone. You'll need to create the ringtone yourself, but it's very easy. Just create a silent sample in GarageBand, then save it as a ringtone.

Read next: Complete guide: How to update iOS on iPhone or iPad

How to block a number on your iPhone when the caller hides their caller ID

It's fairly well known that basic call blocks are easy to bypass. (As we state at the end od this article, we encourage readers to respect call blocks and attempt to bypass them in emergency situations only.) All you need to do is hide your caller ID; you can do this in your iPhone's settings, or enter a country-specific code on a call-by-call basis. With no caller ID, the iPhone doesn't know who's calling, and therefore can't block the call, although it will indicate that the number has been withheld, that there is no caller ID, or that the caller is unknown.

(It strikes us as odd that Apple doesn't give you the option to block all unknown calls. Android offers this feature. It would be a good one to think about for iOS 10.)

Fortunately, for those who are being harassed by persistent, abusive or stalking callers who know about this simple workaround, there are some options remaining. Here's what you need to know in order to block an unknown number.

Is the number hidden, or simply unknown?

Firstly, it may be worth clarifying the difference between hidden and unknown numbers.

Unknown are those contacts that your telephone company cannot recognise. (Calls from telemarketers tend to come under this category.) Whereas a hidden number, also called a private number, is the contact of someone who is consciously withholding his or her caller ID.

But in both cases, you cannot call back or see the number on your phone. The blocking method that we have described before is not going to work with private and unknown calls. So, what to do in those cases?

How to block a hidden number on an iPhone: Download a call-blocking app

There are some apps available from the App Store that can block calls from hidden numbers.

Call Bliss (£7.99) is one of the more popular ones; it silences unwanted calls or sends them to your voice mail.

CIA (free) is another app that is able to get the caller ID and other personal information of those behind unknown numbers.

However, we cannot vouch for the reliability of these apps (CIA even claims that it can get names and addresses of hidden or unknown callers, and we cannot help feeling dubious about that); plus, they are usually paid apps. Some others might be free but have in-app purchases, meaning that you'll need to pay in order to upgrade them.

How to block a hidden number on an iPhone: Use Do Not Disturb

Another option is to customise Do Not Disturb in order to silence calls from the contacts your phone doesn't recognise. What you need to do is to go to Settings and scroll down the tool list until you find Do Not Disturb. Tap on it, then Allow Calls From, and finally tap on All Contacts. In this way you will receive calls only from those listed in your Contact list.

The problem with Do Not Disturb is that it will silence all the other numbers. You might miss an important call from a number that doesn't appear among your contacts. (You will get a missed call notification, however, and they can leave a voicemail.)

How to block a hidden number on an iPhone: Subscribe to TrapCall or other call trapping services

You could also subscribe to TrapCall, a service that finds out the caller ID of hidden or unknown numbers and blacklists unwanted calls.

Apparently TrapCall does its job; it is rated 4+ in the App Store and has good reviews.

However, you need to pay in order to subscribe to its plans. TrapCall offers three different services and their prices vary depending on the level of security you need.

How to block a hidden number on an iPhone: Contact your phone company

You may also try to contact your phone company and see which service does it offer.

Some might give you a pay-monthly plan that gets rid of marketing calls, or change your number if you are constantly getting ID-withheld phone calls. In some cases the phone company might also be able to identify the number behind hidden calls, but then the network provider can only give the number to the police if an investigation is under way.

However, in terms of blocking a hidden number, we are afraid that the majority of phone companies cannot do much about it.

Have I been blocked by an iPhone?

What about when the boot is on the other foot? How can you tell if someone has blocked your phone number on their iPhone?

The sad truth is that you can't tell for sure without stealing their phone and checking the blocked list. (Or you could always, you know, ask them.) But there are definitely clues, to do with the length of time your phone rings before being diverted to voicemail: a blocked call will always ring exactly once, as far as our experiments show.

We look in more depth at some of the clues that let you know if you've been blocked in a separate article: How to tell if someone has blocked your phone number on their iPhone. But having read the above article, which looks at this issue from the point of the blocker - a person who may feel harassed or fearful - we would always encourage readers to respect call blocks and attempt to bypass them in emergency situations only.

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See also:

How to jailbreak your iPhone

How to update your iPhone or iPad to Apple iOS 7

How to stop iPhone neck and iPad shoulder

How to fix a water-damaged Apple iPhone

How to protect your iPhone from thieves