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.


If you mean standard 3G video calls (3G-324M) then no, the iPhone does not support these (and I doubt any (legal) 3rd party apps would be allowed that deep inside the phone).

If the other party does not have any other possibilities besides 3G video call, then I guess your only possibility would be to get yourself a phone that supports that.