I'm Geordie with AT&T Spring. I'm going to show you how to block a cell phone number. I'm going to show you how to block a cell phone and in doing so, this means that any phone that you call using your cell phone that has a caller ID will not be able to identify your 10 digit mobile number. It's as simple as entering in a code before you dial the 10 digit number that you want to make a call to. The code is *67 followed by the 10 digit phone number and then placing it as a regular call. This is going to allow the person that you are calling not to see your 10 digit number but it'll display on their caller ID as a private or blocked number.