OK, that makes no sense.
Yes, it's good to be cautious about giving out information, but your local, private LAN IP addresses are not accessible from outside your house.
No, you don't "contact Google Voice...".
You should have a Google account, for example,
yourname@gmail.com, to which you have added the Google Voice service by signing up. You should have obtained a Google Voice inbound telephone number.
You then go to the Google Voice settings page, to add a check mark to the left of Google Chat, and then add any other forwarding phone numbers you may want to use.
Here are my complete setup instructions:
http://www.obitalk.com/forum/index.php?topic=8560.msg56460#msg56460The instructions assume you are using the old, "Legacy" version of the Google Voice settings page. To get there go to this page:
https://www.google.com/voice/b/0#inboxIf it opens up in the new Google Voice interface instead, then click the three-horizontal "hamburger" icon in the upper left corner of the page, then scroll down the left side and click on "Legacy Google Voice." Then, click the gear icon in the upper right corner of the page to get to the settings page.