Apple gave iOS 5 users minimal functionality in the iOS Notification center. You only get quick access to few widgets and other notification alerts. However, with a Cydia tweak, you can get a Dial pad in Notification center.
NCInstaCall is a Cydia tweak, of cours for Jailbroken iPhones, that lets you dial numbers, make calls directly form iOS notification center.
NCInstaCall is free on Cydia store available via Big Boss repo. After installation you’ll have to enable it from settings > notifications center > NCInstaCall > enable.
When enabled, a new dialpad widget would appear in the Notification Center. One downside is that there is no address book support in NCInstaCall, at least for now.