The Siri personal assistant on Apple's iPhone 4S can now be configured to offer many more features, thanks to a program for jailbroken phones.

AssistantExtensions has been created by iOS developer K3A and can be downloaded onto the iPhone 4S - or any iOS device running a ported version of Siri - from the Cydia app marketplace for free.

While still in its infancy - the iPhone 4S was only given an untethered jailbreak on 20 January - there are already several useful add-ons for AssistantExtentions; Lingual Plugin lets Siri translate more than 30 languages, for example.

SiriToggles is another application available free from Cydia that can give Siri the ability to turn on and off services like Airplane mode, say how much battery life is remaining and adjust screen brightness when requested.

The ability to turn on and off services like Wi-Fi and Bluetooth, and chat more freely with the "humble personal assistant" are also possible thanks to the application.

Talking with Siri can be a formal affair as, no matter how understanding Apple claims users can be - Siri isn't much of a chatter; but AssistantExtensions allows for a more freely flowing conversation.

Say "let's chat" and Siri will reply with "Yep! Just a moment please until I load my brain...OK. I am ready!"

Quite how useful this feature will be remains to be seen, but being able to dictate tweets to the Twitter app, launch applications and ask for translations are all features that will enhance the Siri experience.

Hands-free Control is another application that takes advantage of the newly jailbroken iPhone 4S and can be used to listen for keywords and act upon them. The app runs in the background and listens - even when the phone is locked - so that when "Siri" is said, the assistant is launched immediately, saving the need to unlock the iPhone, or even touch it at all.

Jailbreaking the iPhone 4S and installing AssistantExtensions opens up Siri to endless possibilities and gives developers the chance to show off while Apple keeps Siri locked up in its walled garden - the company does not yet allow developers to create plugins for Siri.

An untethered jailbreak for the iPhone 4S was made available by the Green Pois0n hacking group, when its Absinthe software was revealed on 20 January; just three days later the website announced that the programme had been downloaded more than one million times.