Basically, almost everything on a mobile device needs to use the network, and almost everything does it via HTTP.

移动设备上几乎所有应用都需要使用网络，而它们几乎都是经由HTTP实现的。

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T-Mobile needs more spectrum to build out a true 4G network and might turn to either Clear or LightSquared for assistance, or it could make a play for Sprint.

FORBES: 4G And Other Wireless Goodies To Expect in 2011

At the same time, rising smartphone penetration and the burgeoning data needs of subscribers using mobile devices such as the iPhone is putting a lot of strain on its 3G network that needs more investment and additional spectrum for strengthening.

FORBES: AT&T Eyes Data Growth With $14 Billion Network Overhaul

This is particularly important for secondhand or other mobile devices that you might buy or receive as a gift, and want to activate on the wireless network that meets your needs -- even if it isn't the one on which the device was first activated.

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