UPDATE: For an easier version of this please visit www.unlockit.co.nz from your iPhone. Thanks to GZ user LennonNZ for this automated solution.
I have managed to activate Data on the new 3G iPhone, However you need to be aware that if you follow my instructions below it could end up costing you A LOT of money, so much in fact, that unless you are loaded I would not recomend doing this!
However if you are loaded or just don't care about the cost here is the guide.
Please note that neither myself, geekzone, kiwi-ise, piksel or any one related to us or the site will in any way take any responsibility if you damage your iPhone during this process or damage your bank balance.
You need a non-Vodafone Sim card (I used an old Telecom Roaming Sim from O2) UPDATE: You can use a current Telecom Roaming Sim card as well, you won't get any service but that is OK, all you need to do is get the extra menu item to show.
1. Remove your Vodafone Sim card
2. Insert your alternate sim card
3. Once you have service go to Settings -> General -> Network
4. You should see an option for "Cellular Data Network" - DON'T Press this yet
5. Remove your alternate sim and re-insert your Vodafone Prepay card
6. The "Cellular Data Network" option should remain, Once you have service press this option.
7. You will now see the Vodafone APN settings for the iPhone as follows:
8. Change the APN to www.vodafone.net.nz and leave the Username and Password fields blank.
9. Press "Network" in the top right hand corner to go back to the network settings screen
10. Press the home button
Now when you try to use Data over 3G or GPRS it will work. (when you are testing it make sure you switch off wi-fi)
To revert back, you need to go through the process again, just don't change the APN when you get to that stage. I thought you could just pop your sim out and push it back in again, but that didn't seem to work. Please note that hard rebooting the iPhone will not revert the changes, you must go through the process again.
Obviously Make sure you have credit or you will not get internet access. Also when you run out of credit it will stop working.
If this works for you please let me know.
Once I get more credit (I used $20.00 in like 5 minutes) I will run through the process again and will post a video to Youtube. Until then happy browsing
Just as a guide it cost me 50 cents to view the main page on the App Store, so beware when I say it is expensive!