Dial a caller ID block code before the phone number: If you are living in the United States dial *67 before dialing the actual phone number, if you live in the United Kingdom dial 141 to block you Caller-ID number and/or name from being displayed on someone else's caller identification device. So for instance, if you want to call 218-333-222, Dial *67-218-333-222 instead. Your caller will see a message which says "caller ID blocked". If you have blocked your Caller-ID permanently for a specific number, dial *82 before dialing the number (in US). This service only applies to every individual phone call.

Block you Caller-ID in all your outgoing calls by default by applying for this service from your phone company. Dial your phone company and have them add the Caller-ID block service to your line. Remember that phone companies are permitted to charge for this service.

Some mobile phone companies allow you to call a person through voicemail. Simply listen for a call option, and then dial the number. Because the call is via the voicemail system, you are basically calling through their phone line, and it appears as a blocked Caller-ID. This method is significantly cheaper compared to the previous method, as it only uses minutes from your plan, which would normally be spent.

Toll-Free Numbers:

When you make a toll free call, or call emergency services like police ,ambulance, etc the recipient might be able to identify your number using a system called Automatic Number Identification (ANI) even if you have enabled the caller-ID block service;

These companies are forbidden to use or give out the phone number, so there is not much of a problem regarding privacy;

These companies are also required to inform you that your phone number has been transmitted to them.