iPhone 4 or later, those are the Apple phone models that can install the latest version of iOS, its mobile operating system. Something that leaves out many users with latest handsets that not only can not access the new features of the system but also to the new interface.
An unofficial solution is to use deWhited00r, its latest version offers the possibility of adapting the system interface to iOS Style 7. A cosmetic change that will not get install unsupported apps or other functions but at least the look and feel.
So if you have an original iPhone or iPhone 3G iPod Touch first and second generation Whited00r will allow, if you install the latest version compatible with iOS device including a modified interface to look like iOS 7. To do so will only have to download the firmware to our device, use Redsn0w to put the device in DFU mode and finish installing Whited00r firware using iTunes (you will have to press alt + Restore to select the downloaded file).
After the device rebooted everything will be ready and only a few extra steps if we want to recover the Push notifications and improve performance a bit. Eye, other apps will still see the same unless you have upgraded to iOS interface 7 and maintained backward compatibility.