August 22, 2011 
SoSly 
A file found within developer builds of iOS 5 suggests Apple is already testing a 4G LTE iPhone. First reported by BGR, a LTE .plist (property list) has been found to have LTE references take a look at the image below:
Could this mean a 4G capable iPhone is coming as soon as October? Apple recently had 4G antenna’s installed in a couple of its more popular stores, looks like we’ll just have to wait and see.
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Been told by 02 in UK (mobile phone provider) that iPhone 5 will not be 4g capable I repeat not be 4G capable! However he was sales guy so take it with a pinch of salt, but my guess is iPhone 5gs/6 is coming next year with. 4G capability! Dont shoot the messenger!