Has someone blocked my phone number on their iPhone? I keep ringing and texting but I can't get through. Is there any way to tell who has blocked me?

Has your phone number been blocked by an iPhone using the call-blocking feature introduced in iOS 7 and retained in iOS 8? In this article we explain the telltale signs that you've been blocked by an iPhone: the way your phone behaves as you (unsuccessfully) try to get through, what response you'll get as you call, text and attempt to leave a message, the giveaway number of rings before you're diverted to voicemail and so on. We'll help you work out if someone has (for whatever reason) blocked your number on their iPhone.

We've also got links to articles that explain how to bypass the iOS call block if you feel compelled to do so (although there are serious ethical and potentially even legal implications that we would ask you to consider - this is for emergency situations only), and how to block nuisance numbers on your own iPhone.

Read next: How to block and report iMessage spam

Who blocked my number? How can I tell if I've been blocked by an iPhone?

What is iOS call blocking? It's a brilliant feature, and exactly what it sounds like.

One of the simplest but most convenient new features added in iOS 7 - 2013's updated version of Apple's operating system software for iPad, iPhone and iPod touch - was the ability to easily block the phone numbers of nuisance callers. (We explain how this works in 'How to block a number on any iPhone'.) You can also block numbers in iOS 8, 2014's follow-up to iOS 7 - and in iOS 9 too for that matter.

This is great news for those who are plagued by calls from persistent telephone sales reps. But what if you're the one getting blocked? How can you tell if someone has blocked you on their iOS 7, iOS 8 or iOS 9 iPhone?

The simple answer is that you can't easily find out for certain; but if you check for the telltale signs you can get a good idea of what's going on. We blocked one of our spare phones to find out exactly what it's like to be blocked - the number of times a call will ring before being declined or sent to voicemail, the response when sending a text - to help us work out when we've been blocked in the future. 

If you'd rather watch our experiment than read about it, by the way, have a look at the video of the top of the article. We first show how to block someone in iOS 8/iOS 7, and then demonstrate what effect that has on the blocked phone, so you can learn the telltale signs.

Have I been blocked? How to tell if an iPhone has blocked you

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Have I been blocked: What happens when you ring someone who's blocked your number on their iPhone?

We rang the iPhone that had blocked us. The phone rang exactly once, and then we were told that the number called wasn't available, diverted to voicemail and invited to leave a message. Note that the iPhone never received any notification that this message had been left.

(As an aside, even though the recipient gets no notification that a message has been received, they do get the message and can listen to it if they choose. If a blocked caller has left a voicemail, you can access it by going into your voicemail and scrolling down to find the 'blocked messages' folder, which will sit below the 'deleted messages' folder. Note that if you've not had any blocked messages the folder itself won't be visible. And there will be a delay between the person leaving the message and it appearing in the folder. Thanks to reader Kat for bringing this to our attention.)

How to tell if your number has been blocked

A single ring and then being diverted to voicemail is the giveaway behaviour you're looking for - but bear in mind that this can also result from the phone being switched off or set to auto divert. 

To rule these out, you can immediately ring again from a different number, or disguise your number using the relevant code for your country (141 from a UK landline, for instance), or by switching off call ID in the settings if you're using an iPhone (Settings > Phone > Show My Caller ID, then switch it off).

Have I been blocked? How to hide your caller ID

This time your number won't be visible and any block on that number will be bypassed. If the phone really is switched off or set to divert, it will once again ring once and then go to voicemail. But if you were blocked, either the person will pick up, or it will ring a few times until you ring off or they turn down the call because there isn't a caller ID they recognise.

Have I been blocked? How to hide your caller ID

Thanks to our reader, posting below under the name 'This is true', for coming up with this trick.

Read more: We've rounded up links to all our iPhone tips and tutorials here: iPhone tips and tutorials, everything you need to know

Have I been blocked: And what happens if you text someone who's blocked you?

What about if you send a text to the 'blocker'?

We tried to send a text message to the phone that had blocked us. Everything proceeded as usual: the text sent, and we got no error message. But the 'receiver' didn't get any message, or any notification.

When sent as an iMessage, the text gave us a 'Delivered' notification and remained blue - our blocked iPhone didn't attempt to send it as an SMS.

How to tell if someone has blocked your phone number on an iOS 7 iPhone

Have I been blocked: How to tell if someone has blocked your phone number

So. Other than the obvious clues - you never seem to be able to get through to someone, despite ringing at various times and checking that you've got the right number - the main giveaway is the way you get diverted to voicemail after exactly one ring. If your call is manually declined, or if they're just not available, then you'd expect the phone to ring several times before you're diverted.

If you're getting a single ring before being diverted to voicemail, and then when you try again with caller ID hidden you get a different response (multiple rings and then declined or diverted, or they pick up) then something is probably up.

Remember that just because you are allowed to leave a message - or because your text seemed to go through without any problems - that doesn't put you in the clear. The blocking process is quite sneaky about letting you (the caller) know what's happened.

As we said, though, there's no way to be certain this is what's happened, so be careful before you start throwing around accusations! And if any amateur sleuths out there work out a foolproof method of finding out if you've been blocked, let us know in the comments or via Twitter. Our thanks to the clever readers who've already contributed techniques for cracking the mystery.

How to tell if someone blocks your number on iOS 7

How to call someone anyway, even though they've blocked you

As discussed briefly above, it's possible to hide your caller ID (or use a code to stop it from being revealed) and thereby call someone who's blocked you. Software-level call blocks can only block numbers if they know what number is incoming - this is true across all smartphone software, and the only way to block someone who hides their caller ID is to contact your phone company.

If you are in an emergency, if you fell out with your parents but need to tell them that someone is gravely ill, or if there is some other exceptional circumstance that you feel justifies doing so, you can bypass a call block in this way, but please bear in mind that the recipient of the call may consider this behaviour to be harassment or stalking, and there could even be legal ramifications. This is not something that you should do lightly.

If you have taken all of these warnings on board, take a look at our tutorial showing How to call someone who has blocked you.

Get your own back: How to block a number using an iOS 7 or iOS 8 iPhone

This is all very upsetting, of course, but call-blocking is actually a very useful feature of iOS 7 and iOS 8. If you're getting calls from a persistent nuisance caller, then it's easy for you to make use of the feature yourself. And now you know what they'll be experiencing.

You can easily block a number from the Recent Calls menu. Check out the process in our tutorial 'How to block a number on any iPhone'.