You might have noticed that declining a call on iPhone is quite tricky as on the main screen there is no option to decline rather only you have ‘Slide to Answer’ option. Therefore Jailbreak community comes handy again as they develop EZDecline Jailbreak tweak which replaces slide to answer option with Accept and Decline button.
EZDecline is a paid Cydia Application for 0.99 US$ but you can install it using the procedure here for trial purposes. However if you like the application please buy it from Cydia.
In order to get this Cydia App on your iPhone, iPad and iPod Touch, make sure you device is Jailbroken. Click here to tethered Jailbreak iOS 5 On iPhone 4, 3GS, iPad, iPod touch using RedSnOw. You can also jailbreak iPhone, iPad or iPod touch on iOS 4.3.5 using RedSnow, iOS 4.3.3 using Redsn0w, JailbreakMe or to Jailbreak while preserving your baseband (software unlock) see TinyUmbrella, SnowBreeze & PwnageTool.