Yes, you can run iOS 7 on the iPhone 4.
That is the iPhone 4 GSM. It was the first iPhone 4 released by AT&T.
The iPhone 4 can only support from iOS 4.0 to iOS 7.1.2. There is no way to get any higher iOS Firmware due to the older hardware that is built into the iPhone 4.
The iPhone 4 can currently run up to the latest version: iOS 7.1.
iOS 5 will be compatible with iPhone 3GS as well as iPhone 4.
Since ios 7 is designed for the iphone 5, it will probably make the iphone 4 slower.
This was created to add support for the Verizon iPhone. No device uses it except the Verizon iPhone 4, as the same feature was added to iOS 5, and the iPhone 4S included iOS 5. It is essentially iOS 4.2.3 for Verizon.
The ios 8 should work on the iPhone 4 now. If you cannot get it to work you should call the company and tell them what is going on. This is incorrect ios 8 will not work on the iphone 4
No, iPhone uses iOS as its operating system.
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Unfortunately, making folders on an iPhone requires iOS 4 or higher. The original iPhone only supports up to iOS 3 software.
Yes you can, but expect some iOS functionalities that are on, say the iPhone 5S won't carry over to the iPhone 4.