How to set up iphone 3G with no sim to use google voice as secondary phone?

[Shonnayy]

I have an iPhone 3G that does not have a sim (upgraded to iPhone 3GS) I would like to turn it into a secondary that uses my google voice account. I also have a sipgate account if needed. Im just wanting to use it as a secondary phone to use on my wifi. . How would i set this up or would i need something else

[rich hathaway]

I have an iPhone 3G that does not have a sim (upgraded to iPhone 3GS) I would like to turn it into a secondary. that uses my google voice account. I also have a sipgate account if needed. Im just wanting to use it as a secondary phone to use on my wifi. . How would i set this up or would i need something else
you cant upgrade yer ip3g to a 3gs bro.it is what it is.but u can use the wi-fi whenever u want,this should be obvious to you,or is your phone stuck in recovery or something?if its not just open the wi-fi and turn the boolean to "on".presto wi-fi working.