Sorry, but not yet. Apple could add this in the future, but it isn't in iOS under Voice Control or Siri currently. If you know who called, you could ask for them by name. Unfortunately, that's the only solution with Siri.
Voice Control is still available on the iPhone 4S, unless you have enabled Siri in the iPhone preferences (listed under the General
menu).
If Siri is disabled, holding the Home button will still launch the "classic" voice control, which does work offline, and also supports a whole lot more languages than Siri currently does.
Best Answer
Think of Siri as your personal assistant. It listens to your commands, learns from your tasks & contacts & replies to voice commands.
Well, they're no longer available for the previous iPhone as the app has been taken down.
The new, improved Siri was developed after it's acquisition by Apple, so I'm pretty sure they would have added their Patented SecretSauce(tm) and in typical Apple style, the details are a secret.