Google Voice is a smart forwarding service that is available in select markets. In the case of my needs, this is a US telephone number which will forward calls based on calling rules that were established. Since the number is a smart forwarding number, I can feel comfortable with giving the number out. You can find out more about the calling rules by visiting the Calling Rules Page. If the need should ever be appropriate where I have phone numbers of people outside of the US, I will also set my international telephone numbers to forward to my Google Voice Number which will then use the rules as mentioned. You can learn more about Google Voice on Wikipedia.