Skype's new video call functionality in the updated iPhone app works, but it could have a significant impact on your data usage every month. Unlike Apple's own Face Time video calling, which only works over WiFi connections, the new Skype for iPhone video calls can be made over a 3G connection. However, 9 to 5 Mac found that those cellular video calls churn through a whopping 3.4MB of 3G data per minute.
Over the course of a one minute video call, the iPhone 4 sent 1.3MB and received 2.1MB of data. That means iPhone 4 subscribers on AT&T's 200MB data plan could make less than an hour of Skype video calls per month over their 3G connection before burning through their allowance. It remains to be seen how well the AT&T network will cope with what's likely to be considerable extra load as Skype users get to grips with the new software.