The upgrade to the latest operating system will let FaceTime users place calls on their cellular network, rather than being restricted to Wi-Fi-only calls. It's a great solution when a reliable Wi-Fi network can't be found, but in this age of capped wireless data plans, will a couple -- or even one -- FaceTime calls devour your month's worth of data?
A monthly 5GB data plan on both AT&T and Verizon is $50 in addition to the talk and text plan of choice. While cellular FaceTime is only available on the iPhone 4S and new-generation iPad, for comparison, according to one test of an iPhone 4 FaceTime call, about 3MB of data were used per minute over 3G service. Using this rule, a one-hour FaceTime phone call would use a scant 0.175GB of data.
However, many customers are starting to move over to 4G wireless service, which generates a bit more data use than its 3G counterpart. According to Verizon's data calculator, 10 minutes of daily 4G video streaming (a service which is currently only available on the new iPad, not the iPhone) uses 1.71GB of monthly data.
With a 5GB-per-month contract, it does seem feasible to stay within your data plan despite the video streaming of FaceTime. But, of course, alongside any YouTube videos and catching up with shows on Netflix, you'll want to monitor your account's data usage throughout the month, lest you face a steep $10-per-GB fee.