Google Voice allows you to make calls using a voice over Interent protocol network. When you make a call using this service, Google Voice will call your phone number and then connect your call to another number. By default, your Google Voice phone number will appear in the caller ID display when you make calls using Google Voice. However, by entering a special code, you can block your Google Voice number from appearing in the caller ID display.

How to Make a Restricted Call on Google Voice - 64