Will Apple's FaceTime app hog your data plan?

Apple's FaceTime video chat service will finally work over a carrier's cellular network, making it even easier for people to make video phone calls from anywhere. But will the new app gobble up bandwidth on capped data plans?

Since it was introduced in 2010 with the release of the iPhone 4, the FaceTime video chat application, which allows people with iOS devices to call each other over video, only worked on Wi-Fi networks. The reason given at the time for the limitation was that carriers like AT&T were afraid of what FaceTime would do to their already overtaxed 3G wireless networks.

On Monday, Apple said during its World Wide Developer Conference in San Francisco that in iOS 6, which is set for release this fall, the app will now be available over cellular networks too. Apple didn't specify if the app would be limited to faster 4G LTE networks or whether it would also work on 3G wireless networks. The first thing I thought when I heard the news was that the video streaming service would likely be a data hog that could cause lots of people to blow through their monthly data caps much faster.

In general, streaming content of any kind can eat up a lot of network capacity. This goes for music services like Pandora as well as movie streaming apps like Netflix. According to Verizon's data calculator, users can gobble up 1.71GB a month of data by streaming video to their smartphone over a 4G LTE network with just 10 minutes of viewing per day. And on a 3G network connection using a smartphone, users can blow through 1.22GB of data per month with just 10 minutes of video chat per day.

But the truth is that the FaceTime video app doesn't use as much bandwidth as other streaming video services. The blog AnandTech measured FaceTime usage over Wi-Fi networks when the service was first introduced. And it found that the app used between 100 and 150 Kbps.

The reason why is that the quality of the video is lower. Because the service has to work over networks with much slower upload speeds than download speeds, Ross Rubin an analyst with NPD Group said, it's likely more efficient than other types of video on the network.

"The real-world bandwidth necessary to run the service may not be as demanding as it is for TV shows or movies," he said.

Rubin said people don't use video chat services the same way they use other streaming video services, such as Netflix. And he said that today people aren't worried about blowing through their data caps due to video chatting services. According to a recent study by NPD Connected Intelligence, only 9 percent of consumers say they do not engage in video chat because they are concerned about exceeding their data plans.

"Video chat sessions are much shorter than people watching movies," he said. "There may be some long business conference calls, but on average video chats last about as long as most phone conversations. They're relatively short."

Still, Rubin and other analysts warned that any application when used over a cellular network with a data cap should be watched closely.

"Any app used excessively can get users close to their data caps," he said. "But in general, I don't think it's something most people will have to worry about."

This is good news for many consumers who were shocked when they blew their monthly data caps in a matter of days when the latest iPad with 4G LTE was introduced earlier this year. The faster network speeds made accessing high-definition video from streaming apps easier. And people didn't realize how much data they were using.

But hopefully, the FaceTime app over a 3G or 4G network carrier network won't create the same surprises. In fact, some subscribers have already been using the app over a cellular network via carrier Mi-Fi technology. Because FaceTime connects via Wi-Fi, Apple iOS device users can still access the app over a 3G or 4G network via a Mi-Fi device that acts like a wireless router connected to the cellular network.

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