AssistantServer Installer is a new tweak for users of iPhones before Siri 4S want on your device.
AssistantServer Installer uses the Google API as a server for Siri Siri responses will not be the same but work, which is important. Spire also need to have installed and configured the proxy as the application itself tells you in your settings. Personally I prefer Sara for example, and his voice dictated that supports Spanish.
You can download for $ 0.99 in Cydia, you'll find ZodTTD repo & MacCiti, which comes standard on the iPhone. You need to have jailbroken your device.
More iPhone News: Sara: Siri alternative to free all devices (Cydia)