Temporary Phone Number Service (Free)

[palswim]

I've been searching this on the Internet, but it seems like every link wants to point to inumbr for a free temporary phone service. I'm sure inumbr/Numbr works well for what it advertises, but they only give a phone number with an extension. I found a survey of a bunch of temporary phone services from 2006, and it seems like most of the free services don't actually work any more. So, does anyone know of a free service for giving out temporary phone numbers (even phone numbers that might expire after a day or an hour)?

Why?
With all of the Google Voice hubbub, I found out that I can only map one Google Voice account to a phone line. But, eventually, I'd like to configure a permanent "Do Not Disturb" line. I don't have a (real) spare phone number I can use, so I'd like to just sign up with a throw-away number that will never receive any calls.

Why Why?
Sometimes I ask questions and people want to offer all kinds of unhelpful advice or challenge the constraints I set forth, or refuse to answer until they know why I ask what I did.

Why?
I wish I knew.

 

[FelixDeCat]

Never tried this before.

 

[palswim]

I thought Gizmo may work for this, but when I try to remove my normal (non-Gizmo) number, Google says "Account must have at least one physical phone."

But, on a related note, Gizmo and Google Voice now work together to provide free VOIP! You can link your Gizmo number in your Google Voice account and you can add your Google Voice account info to your Gizmo account, providing both incoming and outgoing calling using your Google Voice number through Gizmo's service.