How To Block Caller ID

How To Block Caller ID
Information on blocking and un-blocking your Caller ID Number when dialing out

Summary
Per-Call-Blocking:

USA: Dial *67 before you dial the number. If you have Caller ID blocked permanently, dial *82 to unblock for a given call.
United Kingdom: Dial 141
Dial “0” to reach the Operator, and have them place the call for you
Dial the call using a pre-paid phone card, or dial from a pay phone
Permanently Block Caller ID:

Dial your local telephone company and have them add Caller ID block to your line. Note that phone companies are allowed to charge for this service