There are many different reasons why you would want to know how to block a phone number on a cell phone. Depending on the exact circumstances, there are more than a few ways to accomplish this.
Two Meanings for Blocking a Cell Number
Referring to blocking a phone number on a cell phone can really refer to two completely different things: (1) preventing certain numbers from calling your cell phone number and (2) keeping your cell phone number from showing up on the receiver's caller ID. The techniques required to perform these two different tasks are quite different, of course, and require their own explanation.
1. Blocking Numbers from Calling You
There are a number of cell phone privacy laws in place and you can use these in your favor if you are receiving a series of harassing phone calls. Generally speaking, two different tactics can be used for knowing how to block a phone number on a cell phone.
Handset Call Blocking Feature
Certain handsets may have a call-blocking feature built into them. To check if your cell phone has this function, go into the contact list on your phone and see if one of the options for a contact is to block it. Alternatively, the settings menu on the phone may have an option for only receiving phone calls from people on your contact list.
Request a Carrier Block
This tactic requires zero technical expertise. Simply call your chosen wireless carrier and request that a certain phone number be blocked from calling your cell phone. The customer service line can be reached by dialing 611 from your cell phone. Some service providers will block numbers for you, but others may not. The only way to know whether your provider offers this service is to call and ask. Remember that some carriers may charge a service fee for blocking numbers on your behalf.
2. Preventing Your Number from Displaying
What if you want to make an anonymous call to someone? This won't help with any anonymous texting attempts, but you can prevent your cell phone number from showing on someone's caller ID or call display. You can choose to have your number blocked permanently or on a per-call basis.
As with blocking phone numbers from calling you, the easiest way to block your number from being displayed is to call your cell phone provider and request that your number be private and blocked. With this request in place, when you call someone, you will show up as a locked number, private number, or some variation thereof. The customer service line for most cell phone carriers can be reached by dialing 611 from your mobile phone. It is also possible to change the name that is shown with caller ID without altering the displayed phone number.
If you want your phone number to be displayed for a single call when you have the permanent lock in place, simply preface the phone number you want to call with *82. For instance, you can dial as *82-555-555-1234.
If you would prefer that your phone number be shown most of the time, a temporary block is probably more suitable. To do this, preface the phone number you are calling with *67. This is very similar to the technique described above, except it will have the completely opposite effect. You can, for example, call *67-555-555-1234 rather than just 555-555-1234. The caller ID on the receiving end will then see your number as private, unavailable, or blocked.
Also Works for Landline Phones
The techniques described here are largely targeted at people who want to block phone numbers on cell phones, but they can generally be applied to modern digital landline telephones as well. To see if it works for you, feel free to give it a test by calling a friend and ask them what they see.