Can You Block a Person's Phone Number Without Him Knowing on an iPhone?by Laurel Storm ; Updated August 23, 2017
Being reachable is not always a good thing. There are several different ways to block somebody on an iPhone; which of them works best depends on whether you only care about blocking phone calls or want to also get rid of text messages, as well as how much you care about the person not finding out he's been blocked.
Blocking Through iOS Settings
As long as you're running iOS 7 or later, you can block somebody from contacting you directly from within your iPhone's settings. If the person you want to block is in your contact list, open the Settings app and then tap "Phone," "Messages" or "FaceTime" – which you tap doesn't matter, since blocking somebody will prevent him from contacting you using all three of these. Tap "Blocked," tap "Add New" and then tap the name of your contact. Your iPhone will automatically block all known phone numbers and email addresses for him. If the person you want to block isn't in your contacts, pull up his information card by tapping the "Info" button from your recent calls list or by tapping "Contact" and then "Info" from the list of text messages you've received from him. Once you're there, tap "Block This Caller" and then confirm.
Effects of iOS Blocking
When somebody you've blocked through the iOS settings sends you a text message, he won't be notified you haven't received it. Similarly, FaceTime will simply report you as being unable to take a call at the moment. If he tries calling you, however, he will hear one ring before being directed to your voicemail. If he's paying attention, he'll know you've blocked him. If he never calls you, this method is safe to use; if you absolutely don't want him to ever find out you've blocked him, however, you'll need to use a different method.
Using a Silent Ringtone
Download or create a silent ringtone, sync it to your iPhone and associate it with the contact entry for the person you want to block for a "blocking without blocking" effect. Whenever he calls you, the phone will ring – but you won't hear it. He can, however, still leave you voicemail and send you text messages, so if you want to block those as well, this method won't work. If he's not the kind of person who gives up after a few failed attempts at calling you, he might also start wondering why you never answer his calls.
Going Through Your Carrier
Your cellular carrier may provide a service to block calls and text messages. Exactly how the service works, and whether you have to pay a fee or not, varies from carrier to carrier. For more information, and to find out whether or not the block is noticeable when the person you've blocked tries to get in touch with you, contact your carrier's customer support.