Many phone companies will let you disable caller ID on your line so your number won't show up when you call people. In some cases, though, you might want to turn caller ID back on when you call certain people so they know it's you calling. You can generally do so by dialing a code to deactivate the private number feature or by looking for a way to unhide the phone number in your phone's menus.
Turn Off Caller ID
For privacy's sake, some people prefer not to send caller ID information when they make certain calls. This will cause your number to show up as private or blocked on the iPhone call display and other caller ID systems.
You can generally block caller ID on a particular call by dialing *67 before the number. This should work on landlines and cellphones alike. Check with your phone company or test the feature by calling someone you know before using it if it's critical that your number be private.
You can also often ask your phone company to keep your number private by default so you don't have to dial *67 before each call. You may also dial *61 to block caller ID until further notice if your phone company supports this feature.
Unhide a Phone Number
If you have caller ID blocked by default, you can turn it back on for a particular call by dialing a code. Generally, you can dial *82 before a call to re-enable caller ID and dial *65 to turn off caller ID blocking until further notice.
Check with your phone company to make sure these codes apply. Some people block or simply don't answer all unknown or blocked numbers, so you may want to try allowing caller ID to go through if you have an unusual amount of rejected calls.
It's not possible to block caller ID for special calls, including toll-free numbers (such as 1-800 numbers) that pay for the call and to emergency numbers such as 911.
Smart Phone Features
Many smart phones enable you to disable and enable caller ID information as you wish.
On an Android phone, go to the Settings menu from the home screen and tap "Call," or access the "Settings" menu from within the Call screen. Tap "More," and then, if you don't see a caller ID setting, tap "Additional Settings." Tap "Caller ID" and indicate whether you want to always show your information, always hide it or defer to your network's defaults.
On an iPhone, tap the "Settings" icon on the home screen. Tap "Phone." Tap "Show My Caller ID" and use the toggle button to turn this feature on or off.