A pair of hackers have installed Apple s previously iPhone 4S-exclusive voice assistant service, Siri, onto an iPhone 4 and fourth-generation iPod Touch. The hack works on jailbroken iOS devices. The version of Siri they managed to install is described as a limited port by AppleInsider. Siri operates literally just as fast on the iPhone 4 as it does on the 4S and is only slightly slower on the iPod touch.
Source: https://threatpost.com/hackers-install-siri-iphone-4-103111/75824/