'Button4Phone' Changes the Call Button to a Round Style in the iOS 7 Phone App
In iOS 7, when you go into the Phone application and visit the dial pad, the call button is a huge green button labeled "Call," and it resembles the power down sliders you see when you try to power off your device.
On the other hand, the rest of the buttons in the Phone application's dial pad are round, so it would make more sense if the green call button were round and the same size; that's the idea behind a new free jailbreak tweak called Button4Phone
by iOS developer GL.CHEN.
Shown above, you can see the before and after effects from Button4Phone being installed. The large rectangular green button is replaced with a round green button that is about the same size as and of the dial pad buttons and has a phone icon in the middle of the button. The button still functions the same as it normally would, so the tweak is merely for aesthetics only. Overall, the tweak looks pretty good, but whether or not you want to actually change it is ultimately up to you.
The developer notes that the tweak is only for iOS 7 and that it has only been tested on iPhones with four-inch displays (iPhone 5 and iPhone 5s). If you would like to give the tweak a try, it's available in Cydia's BigBoss repository for free right now. The tweak doesn't have any options to configure.
iPhone running iOS 7.0-7.0.6
iPhone 5 running iOS 7.0.6