Add Data plan on your iphone w/ Go phone services?

In order to add data plan on your pay as you go/ Go phone you need to change the iphone APN (simply put phone carrier data id )
to change this you need to open safari and look www.unlockit.co.nz, make custom it for at&t APN and you are set. ( to delete this go to setting, general, network)

Now if you have iphone but using an AT&T plan but no data, but get charge for data because you accidently hit safari or email. well, you can use the link above and download a fake APN to block it.

Update: if you have iphone 4 ios, there is an option to turn the cellular off, hence no need to for this.