Apple kept the feature for later updates, including the most recent iOS 11, so the vast majority of currently active Apple smartphone can prevent nuisance callers from getting through if they choose.
This is great news for those who are plagued by calls from persistent telephone salesmen and other pests. But what if you're on the receiving end? How can you tell if someone has blocked you?
In this article, we explain the telltale signs: 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 you.
What happens when you ring a phone that's blocked you?
We blocked one of our spare phones to find out the number of times a call will ring before being declined or sent to voicemail, the response when sending a text and so on, all of which will help us work out when we've been the victims of this feature in the future.
We rang the iPhone that had blocked us, using a landline and then another iPhone. In both cases we (the caller) did not hear any rings at all: it went straight to voicemail. (This suggests that something has been changed in the past year or two - the last time we ran this experiment it consistently rang once and then diverted to voicemail.) We left a voicemail, but the recipient of the call did not receive a notification of either the missed call or the voicemail.
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 you've got visual voicemail, you just have to scroll down and find the 'blocked messages' folder, which appears under the 'deleted messages' folder only if you've had such a message. If you have to call your voicemail inbox, follow the usual procedure and it will report 'one new voicemail' and play the blocked message as usual.
Ruling out other possibilities
To rule out the phone being switched off or set to auto divert, 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).
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.
What happens when you text a phone that's blocked you?
We tried to send a text message to the phone that had blocked us. Everything proceeded roughly as usual: the text sent, and we got no error message. It was sent as an iMessage, and the text remained blue - our blocked iPhone didn't attempt to send it as an SMS.
However, there was a bit of a giveaway. We didn't get a Delivered notification; in fact the person we were texting had read receipts switched on and we didn't get one of those either. And unsurprisingly the 'receiver' didn't get any message, or any notification.
The other possibility: Do Not Disturb
There is, of course, another possibility. Your friend may not have blocked you; they may have just activated Do Not Disturb mode and thus, on a temporary basis, effectively blocked everyone.
If they are using Do Not Disturb mode, the potential solutions and workarounds are slightly different to the ones you use to get round a user-specific block. To find out more, read how to tell if someone is using Do Not Disturb mode.
How to call someone even though they've blocked you
As discussed briefly above, it's possible to hide your caller ID and thereby call someone who's blocked you. Software-level call blocks can only work 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're in an emergency, or 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.