Caller ID has become a standard feature for any landline or cell phone. It allows the people you're calling to see your number so they can filter out unwanted callers. However, if you value privacy and want to prevent your number from showing up on other people's IDs, there are simple steps you can take to block it out. This method works on both landlines and cell phones.
Open up your phone and press the "*" button. This button is located on the bottom left corner of the phone pad. If you are using a GSM network (Global System Mobile Communications), dial the "#" key.
Press "6," then press "7" on the dial. If you're using a GSM network, then dial "31#."
Enter the number you wish to call and press the "Send" button on a cell phone or nothing on a landline. Your phone will then call the person, but your number will be blocked from caller ID.