Google Voice Number / Mobile Phone ?

Do you have an android or smartphone?

it's an Android 4.0.4 / Samsung Galaxy S3

In the Google Voice App go to Settings and set the "Making Calls" option to Always make calls with Google Voice.

would this work even if I have no data service? put another way, is this eating at my data amount?

I'm not sure but the call goes over your cell plan and minutes, not data. The connection though might use a few bytes of data though to access your Google account, though it is negligible.

I made the change. It now calls using GV (even when there is no data connection!). BUT there is still a small problem: the number that appears on my mobile phone (when dialing out using GV) is some unknown (random?) number, not the number that I'm calling. Say I'm calling 212-333-4444 it shows 617-234-1234. It is in fact calling the right number but what shows is the number that GV is using. The problem is that when I look at the log I can't see who was called nor can I try to recall that number.

That threw me for a loop too when I first noticed it. "Who are these numbers?" No idea why GV does this but apparently that's how it works.

If you look in your phones recent calls though it shows the correct numbers being dialed and you can initiate a call from there as well.

If my phone recent calls would show the correct number that would be find, but in my case it doesn't, it shows the fictitious one that Google used.