This script give your Google Voice a SIP Number (as well as a Skype number), which people can call without calling through real telephones. It also allows you to add phone number aliases (even International numbers) to your GV number so people in other areas can call your GV number as a local call, or at least without International calling fees.
This script lets you forward to any SIP (or regular) number using a US number that you choose as a forwarding phone. I also added the ability to record outgoing calls, and automatic GV number verification, which can be used for people who don't have any US numbers to verify their new GV accounts. Also you can use this script to forward to numbers with extensions.