There are all sorts of reasons to block a number: an ex who won’t stop calling, telemarketers who can’t take a hint, or an aunt who wants to check in and see why you’re still not married.

When your phone has buzzed one more time than you can take, you know it’s time to block that number. But how? Here are the steps to take by popular operating systems and carriers.

Operating Systems

iPhone
If it’s a voice call you want to block, make sure you have that number in your Contacts lists. Then go to the Phone app, select the contact you want to block, tap Block This Caller, then Block Contact. If you think they’ll sneak a peek at you with FaceTime, then go to that app, enter their name or number, and follow the same steps. For texts, go into Messages, select the person you want to block > Details > the “Info” button on the top right > Block This Caller > Block Contact.

In related news: If you think you’re the blockee not the blocker, you can be (almost) sure if they have an iPhone running iOS 7 or above. When you call them, are they unavailable? As in actually unavailable in that the phone rings once and then you get a message that the number is unavailable and you’re sent directly to voicemail? Then you’re probably blocked. If you try the text route, then you’d likely not see “Delivered” ever appear under your iMessage and you’d see it switch to the green of a text message.

Android
Go to the Phone app and select Call Settings > Call Rejection (ouch) > Auto Reject List. Type in the number or search for it, select it, and you’re done.

Windows
Go to Settings and then Call+SMS Filter, accept the Terms of Use and Privacy Policy if you have not already, then switch Block Calls to On. Now go to the Phone app, hold down the number you want to block, and hit Block Number, then OK.

BlackBerry
For newer BlackBerrys, you need to contact your wireless carrier to block a number.

Carriers

Verizon
You can block five numbers on each Verizon account that you have. The block lasts for 90 days. Log into the Verizon website, go to My Account and then Manage Verizon Family Safeguards & Controls. Go to Call & Message Blocking Feature and select Add Now and add up to five numbers. If you want or need blocking to be permanent, then sign up for Verizon FamilyBase, which gives you blocking and parental control over your devices for $4.99 a month.

AT&T
AT&T gets very specific when it comes to blocking numbers and wants you to do so on a device-by-device basis, so you’re better off sticking with the instructions above that are specific to your OS.

Sprint
First sign in to your Sprint account, then choose My Preferences, go to Limits and Permissions, then Block Voice, and select Block Only the Following Phone Numbers for Inbound and Outbound Calls. Enter the number or numbers and then select Add Number and Save.

T-Mobile
Go to the Home screen, then select Phone, then Contacts. Navigate to the contact you want to block and select Block. If you want to block callers via T-Mobile’s site, you can only do so if you have a family plan. Sign in to your account and then select Tools > Family Allowance > Access Family Allowances. Go to Allowed Numbers and choose Never Allowed and put in up to 10 numbers that you want blocked. Make sure to click OK and then Save.