How can I make a 3G video call (not Facetime) from an iPhone 4 to another brand's 3G phone? How can I make a 3G video call (not Facetime) from an iPhone 4 to another brand's 3G phone? Is it possible by default? or any apps?

Edit 11 November:

I just found this today: No 3G video calling on iPhone 4
Yes, you can use Skype for that, if the app allows 3G video-chat. Skype is available for a lot of platforms. When you are at home, you can also use Skype on your computer so you don't have to use your (probably limited) 3G network.