Actually the iPad charger is virtually their universal charger.... says so on the website. The only reason they don't include it with the iPhone is because it's a LOT more expensive to make iPad chargers than it is to make the very simple iPhone charger....
Here's a link AGAIN to Apple's website showing the iPad charger is COMPATIBLE with all iPhones, iPads, and iPod Touch's. In fact I am linking to the NEW iPad charger that is 12w instead of 10w.
http://store.apple.com/us/product/MD836LL/A/apple-12w-usb-power-adapter?fnode=48
STOP passing off false data. Maybe you have a bad charger in some way or a bad cable. Either way, there is enough evidence on these forums and Apple's own documents to prove you are wrong.
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Yes you can virtually use ANY wall adapter that has a USB charging port. However, with that said: Most of those wall adapters only put out the Maximum amount of Amps that a USB port can which is .5A (500ma). The iPhone charger actually puts out double that at 1A so if you use one of those wall USB chargers it will probably take twice as long to charge....