If you’re looking to block Caller ID it’s very simple.

In the US

Dial *67 before you dial the number and it will block the Caller ID.

In the UK

Dial 141

Alternatively you can…

Dial “0″ and have the operator dial the call for you.

To permanently block Caller ID you can call your local phone company and request that they block your line.  It is important to note that the companies are allowed to charge for this service, and most of them do.  Once you have this active if you want to unblock a call you can dial *82 before dialing the number.