When iOS 6 launches this Fall, having a cellular connection for FaceTime will be a welcome change for many users who don't have ready access to a Wi-Fi hotspot. But analysts question whether today's 3G networks could offer sufficient bandwidth to handle the live video coupling, or if 4G LTE being rolled out by the major carriers will be affordable when data plans are used to support FaceTime.

The 4G LTE being installed by AT&T and Verizon Wireless (and expected from Sprint this year) is about 10 times faster than their older 3G -- with average download speeds of more than 10Mbps. Meanwhile, the next iPhone is expected to support LTE when introduced later this year.

Apple's FaceTime over cellular announcement "implies that 4G is coming in the iPhone 5," said Ron Enderle, an analyst at Enderle Group.

Without LTE, a 3G connection with an iPhone 4 or iPhone 4S could be frustrating for users, since even Wi-Fi connections over FaceTime aren't always clear and sometimes don't have synchronous voice and video streams.

Wi-Fi data rates over 802.11n max out at 450Mbps, according to . Many more commonplace 802.11a or 802.11g Wi-Fi connections max out at 54Mbps, still many times faster than the LTE being introduced in the U.S. Wi-Fi over 802.11b is rated at up to 11Mbps.